Am I being a Psycho Ex-Girlfriend?

So I was with my fiance for two years. We had an explosion of a breakup that included me going on 2 dates with another guy and letting my best friend and her fiance move in. My ex decided it was best to move out and stay friends. Well, I found out that he had been on a date with a friend of mine that I have been friends with for 15 years. So the feelings from both parties was some major betrayal. Since my 2 new roommates were home we brainstormed some ideas to do to his things that wouldn't damage them, just make it a pain in the rear to fix. So we let the air out of his bicycle tires and took the strings out of his guitar. He came home that night telling me that they kissed, sending me further into a rage. Clearly, I am not over him. This whole break up was a mistake and I fully admit to that. I am no longer seeing the guy on the side and he claims he is not seeing her anymore but doesn't want to get back together. I am still in love and want to get him back. Am I being too psycho?