Hi @Ragingoverlife
I saw your post when it first appeared but I needed time to think how to reply. I've been in a similar situation with my son, except that there wasn't an issue with debt and I didn't have to get involved in his finances. My best guess about the banks and similar institutions, though, is that they will take the documentation that you have seriously.
The matter I have more experience of is my son being out of hospital when he desperately needed to be in hospital. He did go awol on a few occasions, but out earliest difficult experience of this sort was shortly after he was first admitted under section. He improved rapidly on anti-psychotics, and was an extremely articulate person, whose challenges were often highly masked. So when he took his case to a mental health tribunal and asked for release from the section, it was granted, and he immediately discharged himself.
All of the people caring for him know that this was a mistake and told us that unfortunately it was just a case of waiting for his condition to worsen enough for him to be re-sectioned, which is what happened.
At this time he was living with us, so we didn't face the same sort of anxieties that you are facing now. But at an earlier period, and during later periods, he was away from home and we did face the horror of not knowing what crises he was getting into.
For him, debt wasn't a problem, but there was substance abuse, risky behaviour, self-harm and suicidal impulses. Every person with this condition is different, and faces a different set of risks, and so I can't generalise at all from my son's plight to yours. But I can certainly empathise with the general situation, and with the horror, fear and grief that you feel.
Your word 'grief' in particular struck a chord with me. But it is a numb, fractured, confused grief, because you are dealing at the same time with all the emotions and tasks of dealing of your living son. It is too much to bear emotionally, and I don't even think it makes sense to think of processing it. It is just a question of living with it. In particular that means distinguishing between the things that you can do, and the things that are quite simply beyond your capacity or control.
For example, don't feel bad about the fact that he can't live with you. And don't feel bad about alerting the mental health team, even though he is angry with you about it. His condition was much too much for him or you to deal with without professional involvement.
It sounds like the finance thing is something that you might be able to help him handle. Could you make a preliminary appointment with a bank, just to understand how they see their role in this? They will have policies and procedures for the documentation you have received from the hospital, I'm sure.
I can't really offer any advice, just solidarity and understanding of what you are going through.