Living with you is certainly an option he might like to have but I was a little unclear about his financial matters.

If he is divorced there are "rules" set up for who pays what and it's not optional. He can get her payments or he can cause the house to be sold (rather than foreclosed) and sell her car if it's in his name, etc. It sounds like he has assets he's not using or that you are not quite familiar with. If that is true then he may not be quite as bad off yet as you imagine or fear.

It sounds like you're a wonderful sister and worried about your brother since you did raise him but he probably should work on figuring out his financial matters himself. It is very nice of you to offer your home to him and there's nothing whatsoever wrong with that (if your husband truly doesn't mind) and I'm sure your brother is glad to have you at his back. However, you might be thinking of his situation in terms of your own worries and how you believe you would feel in his situation and that might not be as much a problem for him as it is for you?