I basically left them and went back to being friends with my old friend who though I was going to go out with his girlfriend which was one of my good friends along with one other guy friend who was involved. All the detail is down there if you want to read it but yeah I just left them because I was always treated like **** even when I did good things for them.

Dude, i can so relate to this. Ill tell you my story which is somewhat similar to yours. Alright well it was me, my friend and the girl. It was more like the trifecta or three amigos whatever you want to call it basically 3 best friends is what we were. Well my guy friend didn't know I liked her, or at least i don't think he did, and she just got off a relationship with my other friend which unfortunately we had to end our friendship. He never really talked to her or would regularly without me being there. She was my friend when my friend( or ex friend) and her were dating. I did like her until she and friend went out and kind of stopped for a few months then when they broke up I kind of started to like her again just by the way she was acting with me. She did flirt with me a lot and this was the time when I wasn't too sure whether I wanted to like her again because if I did go out with her I would lose my other friend...which ended up happening anyways I basically hinted to him (ex best friend) that I would never go for her as long as we are friends. But when our friend ship ended I was like why not go for her? She did ask me out but I had to reject her for that specific reason which I didn't mention to her. She kept telling me she would never go for blonde guys for a boy friend, hinting she would never go for my current friend which did like her. This was all happening while me and my (ex friend) were still friends. I went and asked her friend to ask her if she still liked me but unfortunately she said no, not in that way but only as a friend. Which kind of hurt but I mean life goes. But then I thought to myself, maybe it's because my current friend and her started to hang out more which gave me the idea she kind of had more feelings for him instead of me. I really was thinking that because he would always be at her place every time i stopped by.her dorm. So this past winter break, around december 17th i believe, he asked her out and she said yes to him... I was honestly in shock considering she said she would never go for someone like him. And a week before this all happened. My roomate confronted my current friend saying things like, "You have been hanging with "taylor" (her name) a lot, I really think you should do something about this. Ask her if she feels the same way you do?" My roomate knew I like her and yet he still did this to me. So i was like F that so i just left the 3 person group and now hang out with my (ex friend) which is now my new, old, best friend if that makes any sense.

I really hope this link helps, Its a scene from anger management
I know how you feel but I can't really say what's best for you except that you always have the last say in everything.

Best thing I can suggest is talk to the guy before you make any decision if you want.
GOOD LUCK MAN!

obv hes not your mate if he new you liked her and now hes that one with her in her bed!