I have an abusive 40-year-old son living with me. I had to leave my own house because of his behavior. He won't leave my house, how do I legally get him to leave?

Call the police when he is being abusive and then ask the police for an order of protection against him.The order will forbid him from coming near you.

I am going to give you a link for domestic violence.

They will refer you to the right place for help. They don't want to know your business,they will not judge you,they are there to help you ! Please seek this help,it will change your life.

Please use this link.These are professional people who can help you.
National Domestic Violence Hotline

All confidential and a lifeline.. please take it.

In a more permanent solution, you evict him like you would any other tenant. Hand him a written 30 day notice to vacate. If he does not leave after the 30 days, you go to court and have him evicted.

But first and foremost make sure you are safe, Do what ever you have to do, regardless to make yourself safe.