There are many of us who have had to do this hard of thing of asking our difficult children to leave and/or not allowing them home again.
I told my 17 year old he had to leave 15 years ago because of his violence, substance abuse, and refusal to honor boundaries in our home. He's 32 now and was just released from jail this week.
I made it clear he cannot live with us because although he is clean right now, he still blames me and thinks I am a mean person for setting boundaries. For my sanity and health I have to keep home as my sanctuary. It breaks my heart because I do love him and know it is hard out there, but I will not allow anyone in my home who does not treat me with kindness and respect.
Like most of us, I believe you have done everything you can. It is up to him to live his own life on his dime, on his time, and in his own space, not yours.