How can I stop my dangerous cyberstalker ex and get legal protection?

Hello everyone, i need help, this is sadly serious, my ex boyfriend has a lot of mental issues, the thing is he is selfish, obsessive, still thinks he is love with me, i broke up with him in 2015, he is an older guy and sadly there is nothing i can do but to either change my phone number or just use a fake name online so that way he won't bother me anymore, he is mad at me because i only like white males which is none of his business, and he is not in good shape in terms of body weight that is a true description, anyway i am very upset because he hacked an iphone 17 i had i took screenshots but my mom is in disbelief that he was hacking me because her stupidity thinks ''he's a good but innocent guy'' the sad thing is he may have more victims in terms of cyberstalking, i blocked him from all social media but that doesn't mean that he could come back with a different number or alias, and i don't want to say this but he has already ruined my life, if the authorites can't help me what other options do i have, i have tears, my mom is mentally ill too

How can I stop my dangerous cyberstalker ex and get legal protection?
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