He goes after 15 year olds

I met this guy, and I thought he was really cool, he drank for me in rage cage because I wasn’t drinking that night, he was really nice and a couple weeks later I had hooked up with him, and my only intention was to do a one night stand kind of thing. After that night he started getting really creepy, he would text me 5 times in 20 minutes if I didn’t respond. Eventually, I just stopped replying competely and he started to leave me alone. I later came to find out that he is really creepy, like he follows girls home and stuff like that. One of my friends younger sisters came into town, (shes only 15) and he tried to get with her. I’m so ashamed of hooking up with him that not even my closest friends know.