What do I do to get my ex boyfriend to leave me alone?

My ex boyfriend won’t leave me alone. In our relationship he was extremely controlling; wouldn’t let me talk to other guys, he told me when I had to see him and he used to grab my wrist really hard until I cried. It was as if he enjoyed seeing me in pain that he had inflicted. We eventually broke up after 6 months because he now accused me of cheating with one of his friends; he even made up a huge story of what happened and told loads of people. My two ‘best friends’ took his side and now are helping with what he’s doing. I was sat at school and he text me telling me exactly what I was doing. He has also recently hacked my a social site and 2 email accounts and changed the passwords. Hemade 7 groups all aimed at how I was a ‘little girl who is a compulsive liar’ and how I ‘cheated with a 4 ft guy because I can’ and how ‘ I cheated on my boyfriend but told everyone at school he did’ It’s started to creep me out because he wont leave me alone and I’m scared as to what he’s going to do next. I now have a new boyfriend, who I’m in love with and I can feel it’s going to ruin our relationship. Sorry for it being so long but could you tell me what I can do next so that he stops? Thank you.