My ex boyfriend and I dated for 9 months on and off all because of fighting, him flirting with my Bestfriends, telling my friends he liked them and one friend liked Him back once and she admitted it to me. But there's a part of him that is sweet and that's what I hold onto and that's what makes me want him as a boyfriend. We broke up a year ago and I'm still not over him cause he is everywhere, he hangs out with my friends and I because my friends like him. So he is always around and flirts with my best friend and she flirts back with the whole touchy,taking pics together sort of thing. Once we were at a party and she put her head on his shoulder as if they were going out! It makes me feel awkward cause #1 she is my friend and #2 he is my ex and it feels weird seeing that. She told me that she didn't like him but I cannot trust her anymore and by the looks of it they aren't just friends. I think she does it to make me angry or to make her ex jealous. So now I hate her my other friends won't support me. I need help! What shld I do?

Your problem is the boyfriend. He was not a very good one if he flirted with your best friend.
How old are you guys, this sounds like middle school and high school stuff.

You have been broke up a year, it's time to get over this. Neither one of them sound very nice.