Need relationship breakup advice - fast

I think I’m running out of time. My girlfriend and I broke up about six weeks ago. She was angry and I acted like a jerk. She tried to talk to me after, and I wouldn’t. Now I heard another guy is trying to hook up with her. I’m freaking out. I don’t want to lose her. I played games, and now I’m sorry. I need to know how to make things right before she goes with this other guy. If I can just get some good relationship breakup advice, something to tell me what to do, I’m sure I can get her back and make things right. But where?