I’m so sorry to hear about what you went through.
It wonderful that it worked out for your son. Mental issues are not easy, and it sounds like you went through hell before your son get his act together. That’s really good, though that he got on medication and is staying with his program.
Unfortunately, my mother won’t do this. She was giving him $350 a month, so although he “lived on the streets,” he wasn’t desperately homeless, which he would have need to have been in order to make the fundamental changes that your son was able to. He supported not only one car, but an Audi as well. As we kept telling my mom, as long as she was giving him money, he had no need to make tough choices, and daydreaming in the park is the easy way out.
After she gave him the $7,000 she did stop giving him the monthly allowance.
He was in jail for a while, and didn’t mind it at all. In fact, he was offered a deal to plead guilty to a lesser crime and get out immediately, and he wouldn’t take it at first. Three squares a day. Finally, his cellmates made enough fun of him that he took it and got out. Jail doesn’t bother him. Prison may, though, but he’s avoided that so far.
He’s been in several times over the years, but doesn’t like it. He prefers the streets, albeit when my mother was helping out. He’s taken medication, but only when he really hits bottom. It “takes the edge off,” as he says, which probably means reducing the highs.
With the current situation, his friend will actually pay him back, bit by bit, which will probably allow him to stay on the streets for quite a while yet. At this stage, I don’t care anymore, I just wish he would stay away from my mother, or that my mother will discover her long-lost spine, and put limits on him. She did say that she’s not going to bail him out now.
Obviously didn’t do his research, or he would have realized it would at least take it until after his 35th birthday. 
Again, I’m glad that it’s worked out well for your son, you and your family.
My mom won’t take the tough steps and won’t talk to my sister or me about it, so I don’t know if there’s anything more to do. Attempting to get my mom to look at reality wasn’t helping and only making her feel more pressure, so we pretend that the elephant isn’t there.