Here's to praying that this weekend is calm and H-less. I believe you have it in your power to make it so. He may tantrum a bit...but, he can tantrum elsewhere. He doesn't live with you anymore. His choice.
I would think that one mention of a call to the police would get him to back off. Maybe, even make the call so you have it documented that he had this convict in the house and you felt nervous enough to call the police.
He will be pi$$ed...but, if his friends are bottom feeders...then, they certainly won't want to help him move anymore. :-)
You don't need another weekend of stress.
"You know, it's times like these when I realize what a superhero I am." Tony Stark/Iron Man
“Focus on what you can do, then do it with all your heart.” Lois Wilson