Ex-Boyfriend Trouble

about 4 months ago I started dating the guy I had been crushing on for three months. That time our relationship lasted about a month before I decided I wasn't ready and ended it. not even a day later he was dating my ex Best friend. someone he knew I couldn't stand. then they broke up a week later and him and I started talking again about a month after that. we became friends again and tried being a couple once more before deciding we were better off as friends. we never talked after that. then out of the blue, he texts and says he doesn't like the just being friends thing, I agree, and we begin dating again. we go strong for a good solid week before he starts gettin a little too friendly with the girl mentioned earlier (who I am now on good terms with again) . everyone thought they were dating so I ended it once again after careful consideration over about 4 days. Now, his best friend who went through a similar situation with one of my best friends, and I decided we are gonna help each other through this. we agreed to talk, hangout, and maybe get a little physical but nothing serious. I need honest thoughts on this. please help.