It does not sound as if he has really learned his lesson so I would not, under any circumstances, pay his foolish, self indulgent debts, with the money from your mother's house sale. Unless he suffers by having to go without himself he will just think the slate is magically clean and start again. After all, you said at the beginning of the post, that you had paid 'outstanding bills' with your retirement lump sum. He is using you as his ATM.
He could try to apply for a 0% interest card as there are several with long payback dates. Pay the debt off with that and then use the payments that go towards interest on the cards he currently owes money to build up a sum to pay back the principle owed on these cards.
There are difficulties with this method. Firstly, he MUST stop spending on rubbish and use the saved cash to pay back his debt or he will make the situation worse not better. Secondly, the whole debt has to be paid back in the set period for the 0% interest as after that the interest rates go sky high and the debt could spiral again.
The hardest thing he will have to do is keep you in the loop. He has been foolish and deceitful and you need to be fully informed of his financial incomings and outgoings.
And again, do NOT pay his debts or you will be doing it forever.
House of the Dragon - good or a train wreck
What sort of family would you not want to marry into?
