Hi Sleepy,
Oh boy does your story sound all to familiar, my difficult child started having trouble around 14. I'm sorry you had to find this site but glad you did. My story is so very similiar to yours only my difficult child will be 34 next month. My husband and I too paid for an apartment and even purchased a small home. Over the years we have paid thousands of dollars for counseling. He has been in and out of jail and is currently homeless. He did have a brief period where I thought he had changed in that he got married but it was all an illusion, he abandoned his wife and 2 children. I have also dealt with the threats of suicide and I have learned it's a way for them to manipulate you into doing something for them.
I understand you want to help him but don't help him in ways that will cost you your sanity, safety or happiness.
It is time for your difficult child to take care of himself. Continuing to allow him to live with you is really not helping him. Only you can make the decision of how much you are willing to put up with.
Oh how I wish I would have found this site 15 years ago, I could have saved myself from so much chaos and pain.
Wishing you peace as you traverse these troubled waters.