Need help, end of nearly 5 year relationship and I'm anxious and worried

Me and my ex recently broke up after 4 n a half years..we broke up for 6 weeks in 2010 saying she wasn't in love with me but we got back together..we got engaged in April 2012 and talked about kids and were actively trying..we moved into a house in June 2012 and she became quite controlling and got mad over stupid things n talked to me like crap,sometimes she was right but most of the time she was Ott over very small things..she left me at the end of February at the drop of a hat and moved out saying she wasn't in love with me.it was a horrible time I got extremely depressed after trying my hardest to get her back she wouldn't..after 6 weeks we were meeting up and she was telling me she could see a future with us both but the next day she said she didn't feel anything despite telling me all these things..1 week later she met me again and said we would take things slow,I rang her later that day and she told me she had been on a date got drunk and went down on as guy and this crushed me and said I could never let it go and she will leave me alone even though she never gave me the chance to..couple of weeks she came back again and moved back in with me and a couple of days later she told me she has feelings for another guy and they have been together for a month and it happened 1 month after we split and she left again...month later she is back and 2 weeks later she left again saying she still had feelings for him..I had enough at this point and tried to move on and was having casual sex with someone to see if it would help but it didn't I thought if she is trying to move on n I've been screwed around for 3 months why not try..was only meeting this girl for a week and my ex comes back wanting to try again and I took her back..so we spent up till the end of November together from July 2013 and things were OKbut rocky,iI found it hard to trust her from all excuses she mAde and lies she told me about this other guy..even a couple of months after we got back together things were good until I found a video of her giving this guy a ******** on her phone and I flipped..said she forgot it was on there and we moved past it..I ended up getting a house and she said she wasn't moving in but still decorated how she wanted it n thought she might get move in in time..end of November says she isn't in love with me and leaves again..2 weeks later she is back but as so called friends calling me babe and darling and having baths together sleeping in the same bed going out together staying at my house then tells me on the 17th that she doesn't want a relationship with anyone and is gonna let me get on with my life even though her saying we are friends and I told her I'm doing it in hope we get back together.. a friend told me a week later she is in a relationship on Facebook and 3 days later she is engaged..looked at the guys Facebook and he actually met her on the 13th which is while she was coming to my house...there's more to it but this is the general points and I am totally devstated, twice she has moved on so quick like we never meant anything..only days before we broke up she was talking about getting our fertility checked to have kids..says she's not in love with me but when we broke up before and she said the same after we broke up she told me that she did really but was trying to deny it...I feel so used that she kept me hanging on till she found someone else.. I know some people might think I'm a dick and my own fault for taking her back but I really loved her so much..engaged after 2 weeks is crazy,she has issues and never seems to be pleased with anything and her moods are always either really high or really low like bi polar..I could never trust her again with all the excuses and lies but why am I the one left hurting n she's got someone?..I have a lot of anxiety and worry from it all,I shake I'm scared I cry no I can't stop in my house on my own,I have my own business and even that scares me after all this..I really wanna find a way to genuinely move on but I just don't know how as everything is scaring me..I'm afraid to go out on a night out as I know she goes out a lot and don't know how I will react if I see them together,it would crush me so bad..I just need some advice,I'm not a dick head I just got heart broken and all I want is to have peace from it..I even get images of them together having sex and its like I don't want to but I have no control over my thoughts..her friends think she is a dick with what she has done to me and her sister has disowned her for being so out of order..how do I get rid of anxiety and be happy with myself..I'm from the UK if that makes any cultural difference to answers given..I wasn't perfect in this relationship and not saying I didn't do things to pee her off but I did a lot for her and so did my family..she even told me she couldn't feel me inside her when we have sex and my confidence has taken a knock

It so happens that most of us choose and adapt to live with the pain and suffering given by the unfaithful partner, despite knowing that you are being used and being a doormat. This happens when you are constricted to the idea of living a different life, as you are so habituated to the life with your partner. The only way to get out of this mess, is to first build your self respect, a person with self respect wouldn't get himself to this state. And you really cannot force someone to love you! there's always someone out there made exclusively for you-nothing is perfect in life though. But atleast you will not be brought to this state. Pull yourself up, cultivate ideas to build self confidence, respect and faith. There's a time for everything, and your time is yet to come. My opinion is based on my personal experience... and yeah, years don't count in a relationship. People in love get hitched within just 3 months and people with even 20 years of marriage together get separated. P.S: Do not compel her to love you only cuz you are obsessed with her.