Why is he staring at me, its making me uncomfortable...?

My ex keeps on staring at me, he broke up with me and this was about 2 years ago. But is seems he still stares at me even though he has a girlfriend and has gone through a list of them. I dont like him staring at me it reminds me of the sexual harassment he did to me at a school dance. We were outside and he kept on forcing me to kiss him and he kept on trying to slide his hand in my dress but I would twist his arm until he yelped in pain since i almost broke it. I defended myself against him and told him I wasn't stupid. That I wasn't stupid enough to be fooled by him and then left since my ride was there. I don't know how I maintained my calm composure, i was just 14 at the time. A bunch of people saw what happened but never helped me out. Im 17 now but it seems he wont stop staring at me and I hate it i feel like an object. I had to go to therapy because of him.

Why does he stare at me?