What to do

So my ex and sons dad is constantly threatening me and being an ass saying I need to go die in a ditch that I’m a waste of space and all these other vile and hurtful things and he expects me to let him take our son idk if I should let him go or not yes we tried doing legal stuff but he wouldn’t go through with it so now it’s up to me weather or not I let him see our son and idk anymore with the way he acts and treats me