How To Get Back At Her.

So I was At home and I call my g.f. I ask where she was and she said, “in bed” and I was like “In your room” and she said “no” and I asked again where are you? She was at some kid’s house.. She said they were just hanging out with him and weren’t doing anything. I trusted her. I believed her. The next day her friend comes up to me at school and says “Your g.f wants to break up and wants a restraining order if you try and call her” So me being me, I called her anyways and Asked her wtf is up. She said she doesn’t like us fighting anymore. and I knew that was bull… So I kept asking her to just be honest, she told me she liked 2 other guys. and one of them was the one she was with. After a while she claims to want me back. And I told her that from now on she needs to be 100% honest. So right then she told me they had sex… I flip, lose my mind, and start having all these thoughts. We have been dating for 2 years now. I find out this kid goes to my school, so I’m gonna find him and wipe the floor up with his face. But that isn’t enough for me. I isn’t. She has cheated on me before. I want her to suffer like I did. I want her to feel the pain I have. I want to get back at her. And GOOD! I want to hit her but I don’t hit girls no matter what. I wanna strangle her but I wont do that. I want her to feel pain from the inside that won’t heal. Please help