My first thoughts were, if you suspected your partner was cheating, enough to go as far as create a false dating-site profile in order to find out, then,
 you must have deemed being cheated on a huge No-No - in which case, why would have you been able to tolerate hypocrisizing yourself?, and
 with cheating occurring on both sides (him, suspected), the relationship was obviously not in a healthy condition [understatement!].
You realise you were, as far as you knew, morally in the wrong on TWO counts, though having led this guy on under major false pretenses?
Do you realise that, no, you have NOT grown 'really close' and do NOT have 'genuine feelings for each other'? That cannot be, can it, given how one party - "you" - didn't/doesn't even exist (aside from in your imagination thus also byproxially in his). Only your attachment is genuine - or, rather, merely FEELS genuine. Your feelings for him should have been built on/in reaction to his feelings for you. But since this fantasy you never existed, the feelings of his that you've fed off weren't real, ergo, neither were your own feelings in reaction. So the upshot is, this was purely a fantasy relationship with fantasy feelings to match.
Because you were at the time already in a relationship, the time was not right for starting one with this interweb guy (and genuine love happens only in strict accordance to Right Person, Right Place, Right Time). That wrong timing was in itself a major preventative to genuine attachment because what happens in this circumstance is that you simply transfer your affections (said attachment) from your erstwhile partner to the new one.
In fact, the person you're still 'in love with' is your ex-partner, just with the negativities that had developed having been extricated.
To explain this more simply, try this analogy: What's gone on was tantamount to you and your ex partner having made a baby together, with you then having convinced some other man that the baby was his (and expecting him to have genuinely paternal feelings for the child and vice versa), on top of which said second man believes at least half of you is another person entirely!
That you went so far as to make, then continue and embellish this false persona (fantasy poster girl), for a further 8 whole months, smacks heavily of you having become victim to a *temporary- and reactive-only* version of Borderline Personality Disorder - due to unabated chronic stress sustained for that bit too long (which I call DefCon3, 2 or 1 - 1 being the highest). FYI, genuine, clinical BPDs are permanently, their whole lives, in DefCon3 because they were stressed out from a young age courtesy of being fed false/180-degree skewed rules of reality, especially human interpersonal-centred ones, whereafter all incoming signals from reality had to be skewed to fit the skewed base reality foundation or else risk the entire grasp on reality present and past falling down (like an upside down house with foundations where the roof should be and none under the building itself - tres precarious!).
In other words, you were at the time incredibly, long-term distressed, stressed, conflicted and confused, which reduced you into whatever degree of survival mode.
You were the one who with complete, exclusive control *fashioned* this false persona out of myriad choices. To have remained unidentifiable by your then boyfriend, you just as easily could have just made yourself a single working mum of 3 *boys*, living in a completely false location, right? Not only didn't you, but note the highly revealing fact that the woman you chose to be was basically the complete opposite of whom you really are in major terms of her life situation and status. You DIDN'T just log onto this site to catch out your boyfriend; that's just what you THOUGHT you were doing at the time. You acted on an, then as yet un-sensed, elusive and inarticulable, deeper-down impulse in your psyche to SELF-MEDICATE - seek a Methadone by which to wean yourself as painlessly as possible off of your Heroin - your unsuitable, unhealthy addiction to the now-ex relationship - as opposed to the Cold Turkey that, with 3 kids' welfares and lives to run, you could ill afford the luxury of.
But the excellent news is: the tonic (of Mr Fantasy Fantasy-Lover) having been administered for an effective period, and your unhealthy attachment to the ex meanwhile having increasingly withered and just about died, you're now coming down - back to reality - addiction cured - proven by the fact of  having ended this panacea relationship and  coming out into a public place to make your confession (and receive 50 lashes or a spell in the stocks).
Because this guy's own life was similarly 'complicated', he was your counterpart at the time, hence why you attracted each other (merely circumstantially). Deeper down, he probably knew you weren't real, but didn't care because of him likewise needing a course of Methodone.
How you move on is actually very simple:
First, recognise that he was NOT amazing TO YOU. To the REAL you, he might have been a complete 'merchant banker' because *you* wouldn't have been unrealistically imperfect like the mere human being you are. It's EASY to be amazing, lovely, wonderful towards a woman you believe is 100% perfect, isn't it. Unlike a real, flesh and blood woman, she never irks, fails to cooperate, disappoints. Secondly - and trust me on this - NO human likewise in DefCon3 is amazing. Quite the opposite. But, again, it's easy to PRETEND one is. So believe you me - he presented as much of a false persona to you as you did to him, meaning, when not on Cloud 9 in La-La Land, he and the relationship with him would have been HELL ON A STICK and gone Splat! within the first 3-4 months, leaving you in almost exactly the same DefCon-ed state all over again, the non-functional state you couldn't afford to be in due to your two jobs (job + 3 kids).
You dodged a bullet. And so did he. You and he merely had a matching giant need which you both managed to pick up on, and tacitly agreed to be each other's temporary salvation. Bish, bash, bosh - job done - and it didn't even cost the pair of you any money nor impede or impose on your routines nor present as self-help WORK (- you turned work into FUN).
So my conclusion is that when you logged on you were NOT cheating... because you already deep-down knew the current relationship was dead and over. You also knew you DIDN'T actually want another long-term relationship straight on the back of the ex one, hence why you made sure it couldn't become real and go anywhere by first erecting a further-flung, impregnable barrier on the path to Relationshipville.
Relax. You're jut very, very cleverly resourceful (and a bit of a risk-taker in terms of boundary encroachment to a fraction of a millimetre).
The residual heartache you feel is partly heartache for your ex relationship (the grief you still feel over the loss of the era and your youth/lost time) and guilty conscience (unnecessary, it turns out).
How you move forward that last few, reverse paces as takes you back OFF the Relationshipville path, is to get back on that or another dating site, this time as yourself...and this time, recognising that you're looking merely for a rebound relationship (real one this time) - meaning kids schmids! - and, accordingly not to mis-sell yourself in that respect. I suggest your profile include blurb along this line: Looking for a soppy romantic - who, like me, needs a limited-period rebound relationship - to spoil me rotten and be spoiled rotten back with fun, stimulation, laughter, support, affection and TLC, and if anything deeper and more lasting develops from that, all well and good, but if not, all well and good.
I imagine that unbridled lack of shame and apology over nothing but total and utter honesty, self-awareness and conscientiousness, in terms of where they stand and might stay standing, will be MOST attractive to a huge number of men on there.
The alternative is to just put one foot in the other through determinedly gritted teeth in the knowledge that the last of your erstwhile attachment and heartache will bog off far more quickly than you anticipate (2 months max).
Hope that all made sense?
PS for future ref: Coming as a ready made family is a bonus to a lot of men, not an automatic negative.
Eight months is a long time to be "unreal" with another person. (even though you say you had 'genuine' feelings)
If I were you, I would come clean with him. Tell all. The truth.
He will either learn a great lesson about online relationships (things aren't all that they seem in these sites - resulting in real shock therapy for him) OR he will want to start up again with you, this time FOR REAL.
Right now he must be dumbfounded that you suddenly dropped him - for no apparent reason.
PS You say he has a "complicated life" and would not "want to hear the truth." Give the guy some credit. He deserves the truth.
Hi and thank you for both comments. when I wrote looking for help and answers I wasn't to sure how It would help me or if it even would help at all I was kinda desperate for help in some shape or form!
But to my surprise reading the comments has helped a lot and thank you for your responses and I've really taken on bored what you have said soulmate and I agree with you just wish it was easier or quicker lol 1 week on and I'm still struggle ruling with my thoughts and of course still pining for my perfect guy which I realise isn't so perfect now, but I see that it was all based on a lie, my lie! It's still really hard and I find myself checking whattsapp to see if he's online and checking his facebook but I'm hoping I soon forget him or move on from this very stupid situation. I've read other online dating problems on this site and it's helped give me some prospective and I hope mine will help someone one day! It's a horrible thought to feel your alone with your problems and I'm glad there's kind people to respond no matter how crazy they are!
Again, how do you even KNOW it was just your lie? For all you know he was nothing LIKE he claimed to be.
Has he been chasing you, ringing the phone off the hook? Hasn't, has he. Guilty conscience, grateful for the opportunity to cop out, same as you.
NO-ONE can stand that level of mystery without acting to get to the bottom of it. Even THAT would have him calling. He knew. Oh, he knew.
"I've read other online dating problems on this site and it's helped give me some prospective and I hope mine will help someone one day!"
... and yet another sign you're virtually out of DefCon. Those with their own survival on their minds don't think about the needs of others. (Tick!)
"I'm glad there's kind people to respond no matter how crazy they are!"
Sh*t, we've been ber-duh-ber-duh-ber-duh-rumbled!... better take these pencils out of my - mwa-ha-haa-CUCKOO! - nostrils, LOL. (Or did you mean you?)
PS: I bet he ponged to high heaven.