Boyfriend issues..... im confused...... HELP me with my BF issue!?

There's this guy I have known for almost a year, he's my best friend's ex but I really like him. He asked me out and then there were some rumors about I gave him BJ's in his school in belfast but it wasn't him who was spreading them. So I dumped him. A week later he asked me back out and said that he was sry, and then this dude forced himself on me and then told my bf that I was cheating on him. So he broke up with me now it's a month later and he asked me back out and I had to say yes but I don't know I don't want him to break my heart for the fourth time, but I like him a lot and he's the one guy that I can actually be myself around.Plus he said when he broke up with me it was the worst mistake he has ever made and that he won't ever do it again but I still don't know if I can trust him. So what should I do wait for him to break up with me and then if he ask's me back out say no or should I dump him before he get's the chance to do it to me. PLZZZ HELP ME MAKE UP MY MIND, BEFORE I MAKE THE BIGGeT MISTAKE OF MY LIFE!!!!!!