So I tend to be a bit of a commitment-phobe, I don't know where this comes from, but I've been like it for as long as I can remember and once I end one relationship, I jump straight into another one. I know and recognise this is wrong, I don't like to be alone or single but I also find I am just never happy no matter what.
1 year and a bit ago my then-girlfriend and I broke up after nearly 2 years because I messaged a girl that I have a history with on social media. All I messaged was 'can we speak' because at the time I genuinely needed someone to talk to about how I was feeling and of course my girlfriend wasn't happy about this and we broke up.
The girl I messaged is in love with me and always has been, we have known each other for a while and always had an on-off type relationship, mainly revolving around sex (its the best sex either of us has ever had) but I would also class this girl as one of my good friends because no one knows me as she does, I'm also very comfortable around her and she helps me through my problems and is always there for me. I literally have to cut her off every time I get into a relationship to resist the urge of anything happening between us because I am so attracted to her, I know this hurts her so bad but I also know she will always be there for me when everything falls apart. There is something about her, I know I'm an asshole but I have cheated on every one of my relationships just to be with her but thats it.
Since my ex and I broke up, I and this girl have been speaking constantly and spending a lot of time together, more than in the past, as I said she spends a lot of time at my apartment, we get on very very well so I love being around her and her being at my place so I usually tell her to stay for days on end, we come home from work, eat, chill and the sex is mental and it makes me happy. We have had pregnancy scares in the past, where as much as I saw it killed her inside, she got an abortion because she could see I was scared and unsure but I can't help but think about those times and how bad I've treated her and she still stays.
The thing is when we were teenagers she had a fling with at the time, two of my close friends, two separate occasions but when I found out it destroyed me so I can't make her my girlfriend and I've told her this but she stays anyway, so I don't think I am to blame for leading her on.
The other day I don't know why I did it but I met up with the ex and told the said girl about it. It got heated and words were exchanged and I told her again nothing would ever happen between us ever and she was very hurt and told me to please do her a favour and never contact her again, so I blocked her thinking she didn't mean it but it's been a few days and I feel sad and miss her and do have feelings for her but now my other ex is telling me she wants to try so maybe I will? but I still miss her and I know I'm gonna go back there again, but I don't know why.
What is the right thing for me to do here?