The credit card idea is a really, really bad one as you don't yet know how or when you'll be able to pay it back. It's the most expensive way to borrow money apart from payday loans and loan sharks. A credit card can also make you feel quite rich, until you reach the limit.
Better to cut outgoings to the bone and see how little you can actually live on, I think. Him being at home for a bit will help, as there will be no travel costs and office lunches to cover. He can do some creative slow cooking with cheap ingredients, too.
When he's finished pouring it all out and you've finished listening supportively, why not brainstorm ideas for getting by on less?
DH and I tried last year to see whether two could eat on £10 a week because some Conservative party official in Bath had helpfully tweeted you could, based on what Jack Monroe did years back with a toddler.
We tried, including some loopy stuff like cutting up 15 budget fishfingers equally to make two meals. Making carrot soup for three lunches from a kilo of carrots was more successful. We concluded you cannot feed two on £10 a week. £15 you can, though. Nobody can eat or drink anything out, though, ever.
What you do about the wedding depends how close you are to paying for it. What if you asked your guests to give money as presents? Might you recoup enough to pay off the balance?
I'm really sorry about the whole messy situation and just wish your DP had been paying more attention the day his training covered conflict of interest. 😕