Why does he still look?

THIS IS LONG BUT PLEASE TAKE THE TIME TO READ IT..My ex boyfriend still stares at me since the break up which was over a YEAR ago.I didn’t think much about it until recently when my best friend mentioned it.She said she didn’t want to tell me because it’s kind of stupid but she said she always sees him watch me walk by..I have been wondering about that lately.Why does he still look? We haven’t even talked since the break-up even though we both agreed to break-up after I got in a huge fight with him and insulted him.Two weeks after the break-up, I ignored him, but then decided to talk to him if he wants to get back together.He said he wasn’t ready for a relationship.That was that and we never talked again.I don’t even look at him.Now if he stares at me because he still has some sort of feelings for me wouldn’t he try and talk to me and not have a girlfriend?He was very different towards me when we were together than he is to any other person.He told me about his dreams and most personal secrets.He even planned a future for us together.I never really believed him until this year when I started finding out he never lied to me and he even told his friends the truth and even defended me in some cases.I also found out that he told his football team that if anyone ever talks or touches me he will beat them up while we were together.I liked one of his teammates this year and talk to him.He always stared at me (still does which I don’t get) even though he didn’t call when he said he would when I gave him my number.I don’t understand any of this.Me and his girlfriend and her friends were all friends but she doesn’t like me at all anymore nor does her friends.My ex told some people a while ago when I passed by that I was his ex.He always looks though.What do you guys think all this is about?Any ideas.I want to find answers!!!Told ya it would be long…thanks for reading.