I am recently healing from a breakup with a girl after finding out she was going out on dates with her "gym buddy" that I "shouldn't worry about". She went on to tell me that there is a reason why all of my relationships end up with someone cheating on me.

This breakup hurt much more than I thought it would. The first part of the pain comes from the obvious missing her and what we had and the second the disappointment about the way I conducted myself in a relationship.

I dealt with so much of her shit, she was separated from her husband and was going through the divorce process and I sat there and tried to make something serious with her. She called me a pussy and even hit me on a trip that we went on and I still left and part of me still wants to stay in this.

I typically don't think I am a bad looking guy as I do have a high body count for being a guy but I think the issue lies down in my self worth and self respect. I feel weak in relationships and let the girl I am with dictate things and don't stand up for myself when I should. I cry more in front of her when I shouldn't even be at all I should of said more about the gym buddy even though it was a coworker she has never seen before but I didn't because I didn't want to come off as controlling and manipulative.

I need to change this about myself and I need to know where to start. I am almost 27 and this is something that I don't want to carry over into my thirties.