My X BF Likes me and another girl but I hate the other girl and him?!?!?!?WHat should i do?!?!?!?

Ok. My used to be best friend (sabrina) went out with my XBF and I hated it when she did so she got this vibe from me that said if she touched him I would kill her! anyways....she dumped him and then he started flirting with me I flirted back as usual but this time he started to flirt with sabrina. I GOT REALLY PISSED OFF! I didnt talk to either of them. then today I was a couple feet away from her and Punched her right in the fACE and she was knocked out. of course I gopt in trouble but he likes both of us and i dont like him but she does. I need help please on what I should do! I am a little jealous