I don't know what I'd do in your shoes but what popped into my head as "advice" was this:
If you can't afford a lawyer, or not the one he wants, tell him so and if you have a legal separation agreement that deals with finances, make this a part of it.
My H was arrested for assaulting me and like an idiot I hired a lawyer instantly to help "save" him from paying the price for his actions. And now having lost my job unexpectedly and owing a lawyer a LOT of money, I regret that decision I made ENORMOUSLY.
If a lawyer is not in the budget he can get a public defender or defend himself and pay for the consequences of his choices.
You certainly shouldn't have to shuffle other bills that impact the whole family simply so he can have an expensive lawyer to save his butt. The time to think about saving his butt was when he picked up that first drink the day he got the DUI.
Just my 2 cents from someone who made BAD financial decisions involving a lawyer and trying to help my H.