Everytime my child's father reaches out, it's not for my child or anything in relation to them.

It's to fight with me or to harass me. I'm in the process of getting custody and going to eventually file for a restraining order. What can I say for him to leave me alone. I want him to stop talking to me and I really want to hurt his feelings so he can just stop being interested in me. I know it sounds fucked up but he's like a cancer! What can I say so he seriously goes away?