Welcome to SR, greenaggie. I'm glad you found us but sorry for your trouble.
Couple of things. I would consider visiting him less often. Give yourself a break.
Also, it's nice that you bring him things to im prove his comfort, but you do not have to be his friends'supplier as well. A firm "no" on that one should suffice. Don't explain, justify, defend, just....no.
Your husband is, hopefully, getting the help he needs. Use his time away to get the help you need.
What is your work situation? Can you take some time off? Sounds a few nights of good sleep would help, as would a loosening of some of your responsibilities.
You may have to eat the missing money. Do you have an emergency credit line or savings to tide you over?
I don't know what to say about his son. Probably keeping the situation status quo is a way to go for now, despite your husband's desire to have him live with him.
Good luck. This will pass.