From the age of 16 he would frequently get in contact with me, trying to "hang" out, ask if I could ever see myself in a relationship with him, he would ask for "photos" of me, have sex with, handjobs, blowjobs, dance for him, pay my bills and so on and so forth. It's disturbing to where I finally blocked him. That is until somehow he went through his mother's FB account, found my profile and started messaging me POSING as his mother, asking questions about what do I think about "her son", and if I still hate him and blah blah blah. He's been doing this obsessively for years, it's so frustrating I want to cry! He posed as his mom to get my current contact info only to text me as his self to end up making making small talk with me to escalating to something sexual yet again. The things he has said really upsets and I don't understand why he is harassing me and doesn't get why it's obviously upsetting. Am I going crqzy here? What is wrong with this person? What do I do to make this very clear to hin that this isn't okay, or will he just never understand or his he playing stupid. I have a great relationship with his sisters but he ruined the family relationship I will ever have with him and refuse to be around him!
Firstly, from your explanation, you both are not related in anyway. Just a close family friend that's all.
Secondly, maybe he's comfortable with you having known you for a whole lifetime, and feels he would be safe with you, or maybe he's just scared to try out things with a random girl he would meet on the street or at work or in the mall.
If you both ever feel like getting on in a relationship, its 100% normal.
You could try change your notion about seeing him as a family and maybe you both could be cool. Or it could be he's not your type. Maybe in height, body built or color. But if its none of the above and its just your notion of you seeing him as a family blood, its wrong in a way and not his fault.
You could just try have a chat with him and tell him why you just not into him and set the gentleman free from your chain of unreciprocal love.
But if after all he's still nudgy and bent on you, please look for the nearest psychiatric hospital and enrol him in( on a lighter note tho)
But at his age, he should be matured enough to understand you after the said polite conversation. Don't dress too attractive by the way to the meeting venue and make it an open place like in a park or in a hospital lounge
Let's cut the cr*p, he knows darn well it's upsetting! And you KNOW he does, his whole modus operandi- sorry, operanDUM proves it!
It looks to me like, once he realised he *wasn't* going to be capable of making headway with you as a girlfriend, the underlying intention of his campaign switched to resentment-based bullying to teach you a lesson (pff) for having rejected him, which his ego has now got hooked on ("ooh, the power!") (yes, pathetic, indeed...the guy obviously has serious ego problems).
Bullies rely on their victim's silence. Be fully prepared to dob the effer in. Preferably, as a first move, to his sisters and mother, leaving your ace card as YOUR dad and his dad both (you'll always be a child to them, see, plus this does originate from a childhood position *they* placed you in, irrespective that they couldn't have foreseen this nasty development)....which will probably be automatic the minute you reveal all to your dad. I imagine his mum wouldn't be too pleased, either, to learn he'd hacked her profile and assumed her identity, and what's worse, for no reason but to use as his bullying and harrassing aid towards the child of a set of close, long-running FAMILY FRIENDS/QUASI FAMILY - do you? And make sure you remember to state that it's been going on practically non-stop (or is it literally non-stop?) for eight- EIGHT!!! long years.
Bullies also rely on your POLITENESS, i.e. sound moral compass. So stop trying to damage-limit (- he's not, is he!) and - akin to what RB's just advised - give him both barrels of an ultimatum - by email or, better yet, recorded, signed-for post (retaining a copy) - as I do not agree you should risk meeting him in the flesh in his hitherto state of mind (no! no! NO!):
STOP CYBER STALKING AND SEXUALLY ACCOSTING AND HARRASSING ME, I DO NOT FANCY YOU, HAVE NEVER FANCIED YOU, *WILL* NEVER FANCY YOU, YOU'RE JUST NOT MY CUP OF TEA AND THERE'S NOTHING ANYONE COULD DO ABOUT THAT FACT, OKAY? I've tried too many times to ask nicely, so now: DO THIS ONE MORE TIME AND YOUR WHOLE FAMILY ARE GOING TO KNOW ABOUT IT (I have saved exchanges and screenshots as evidence). AND IF THAT FAILS - THE POLICE. YOU HAVE BEEN WARNED. CONTINUE AT YOUR PERIL. And whilst I'm at it - well done you for spoiling what was once a perfectly pleasant and decent relationship between our two families!
(I take it you do have B&W evidence? If not, just bluff it anyway.)
I know it feels out of your comfort zone, but - needs must. Otherwise...put it this way: these things don't tend to get better. *As you can now - eight long years later - appreciate*, yes?
I would recommend not owning a Facebook, and just try to keep in touch with family over phone and in person. I would probably bring to light everything that this guy has been doing, and make it known that his advances are unwanted.