Should I retaliate?

I recently cut off and ended a friendship with my former bff. For seven years I was his friend. He would treat other people better than me and he would make fun of me and he would sit there and call me a bum, a cow, and other stuff since I told him off the other day (in a nice way). Now, I have been talking to some guy that my sister’s boyfriend introduced me to for a while. Before I ended the friendship, I told david about him. Yesterday, the guy I had been talking to called me. I was telling him about my intentions to buy the house that I grew up in from my uncle. He would call it our house. I never told him I wanted to be his girlfriend. I don’t even like him like that. I was wondering why he was acting weird. I told my twin sister about how weird the guy was acting. Keep in mind she is still friends with my former friend (I really dont like him now) and can read his comments on FB. She told me, “Oh. I think I know why he was doing that. It’s because David told Zavier (the guy) that you really liked him.” …:/ What?…this was after I cut him off. When my sister told me that, I hung up on her. I told that little bastard david that I didnt like him and he goes and does this?! Should I retaliate? I can mess that bastard up so bad. I am not a biyotch btw. My mom was like to just deal with it. I have dealt with his crap for 7 years and just put up with it. I have dealt with people putting me down and all this stuff from middle school and up until now (im 19). I do not want to deal with his crap. Should I retaliate and if so how? can’t I sue him for Harrassment and posting my personal issues on fb? Ya’lls input is greatly needed. His dad is in prison for pulling a Michael Jackson and his mom dumped him off with his grandma and kept his other brothers. I can tell why nobody wanted him.