Seriously, when do you throw in the towel

I am married to someone that is a living, breathing, trainwreck. He has ADHD and more recently we found out he also seems to have a personality disorder. We are stuck in the same cycle. Things are bad, he gets help, takes his meds, best husband ever! Things get good he refuses to take his meds everyday, he knows better than anyone else, he can do no wrong at work because everyone is his BFF and would NEVER fire him (gosh no!), he's a tax expert, a doctor, and even if you tell him you've been there /done that and he hasn't, he STILL knows better than you. And when the SH**T hits the fan he's shocked! Totally shocked. And then its violin time, poor me, I just made a mistake, I shoulda stayed on meds, I shoulda listened, I hate my life, I keep screwing up, I'm no good, I feel so guilty, whaa whaaa whaaa.

He is a kind,  loving man and a wonderful father. He would be the man of my dreams if he didn't have these problems, but instead he is dream killer. He is becoming a pariah to the family because he is dragging us all down into the vortex of his tornado of destruction. So much potential so much talent covered in a wall of impenetrable crap! He has an entrepreneural spirit but everything he tries to do go down in flames because he does random crap, says the wrong thing, or acts before thinking.

He feels awful about it. I feel awful about it. He is scared to death, he's hopeless, I think he's helpless. We just gave up on him maintaining employment. Umpteenth job he didn't even last 3 whole months. We are in debt up to our eyeballs,  we have nothing to look forward to or backward too. Why do I bother to save money? OH yeah just for his next disaster to wipe it out. He got banned from his Psychiatrist office because he kept making appointments and forgetting to go to them. So he is even in debt with them!

And our poor little girl loves him the best and I love him the most.

What do you do with a person like this? We are at wits end. Can't put him in an institution, he's off but not off enough for that. But its clear he won't be able to take care of himself by himself.  He has no job, no car (that got repoed) and no where for him to go. If I give him the boot he'll have no health insurance either.  He talks about sleeping in his storage unit or in the park if I ask him to leave. He seems okay with that?  Really, your okay with sleeping in a park? Parents are at lost, I'm at lost, friends are at a lost, he's at lost. He is starting therapy again.

Wondering if now the time to just say screw it.