What can I do about my ex?

It’s ok if he moves on and is in a relationship but its not ok for me to do it? I’m not saying I let him get involved in my life but my question is what can i do for him to stop/protect myself. (I actually don't let him get involved. He finds out this info and I only tell a small amount of people, and then he has his "buddies" figure out who the guy I am seeing is)

He has been dating a girl for three years they also plan to get married in the summer. However when a man tries to enter my life or tries to date me he doesn’t like it and goes and messes it up. (By talking crap about me, by hitting or going up to a guy who shows interest in me) (I also haven’t seen him in 5 years and this past summer was my first time seeing him again). I confronted him about our past relationship since we were so toxic and he said to me "I still love you but I can't be with you because I already promised another girl that I would marry her"

If it also helps he has anger issues like very bad anger issues and in the past has hit my ex boyfriend. The reason why he hit my ex boyfriend was because he found out him and i were seeing each other, He went up to my ex and asked him "What's between you and Tara" my boyfriend at that time replied "I love her" and he punched him for saying that, He also had my cousin spy on us. Also tried another time to beat up my boyfriend at that time by trying to take him somewhere far so he can beat him and my boyfriend got away.

I was also talking to his cousin once on Facebook and we just had normal "Hey, How are you" conversations and I wake up one day and see that he has blocked me for no reason. I believe that reason was because of my ex. But I now have been dating someone else and he doesn't know and i intend to keep it that way. Do you guys think this behavior will stop when he gets married and has kids? Advice please?
What can I do about my ex?
Add Opinion