Always thinking about the past

Well the story is is that me and my ex went out for about 9-10 months. He was a real jerk and cried and begged me to stay with him but eventually I convinced him to let me break up with him after 3 hours on the phone with him. But anyway resently my...

sisters boyfriend has been asking me what me and my ex did sexually. I tell him it is none of his buissness because I know he will tell my sister and my sister will tell my parents but he doesnt stop asking. Also he is over like everyday so I cant avoid him and I think my ex told him about that stuff and it gets me annoyed because my ex would go around telling everyone everything I said and twist my words around and other stuff too. What should I do about my sisters boyfriend. Am I overreacting. It is really bothering me now. Thanx for all the help.

What ever you do you should do it after taking consideration all the points.