My first marriage ended when my ex chose to spend our final £10 on alcohol.
I'm so sorry OP. I can only imagine the fear / upset at the prospect of potentially facing into something similar again.
Thank you for asking about me. Well, it's 8 years later, my 3 kids were very little when he left & trying to work / manage them / pay bills was really hard, but I managed. On one level, he pays something at least, if not anything near what he should. Trying to regularise our situation has been a nightmare (I'm in Ireland so until recently you had to be separated 4 years before could apply for divorce & he has made it extremely difficult to process but I'm finally in sniffing distance of it!). However, I've a good job, the kids are doing fine, and although money is a challenge, I've never had that stomach-churning fear of checking my bank balance to see I've nothing or watch him stroll in with a top-of-the range bike when we'd no money for groceries, and that's invaluable.
Everyone's situation is different and if hesitate to say LTB, but absolutely frank, all cards on the table conversations are needed. You can't live a proper life or have any marriage when you've no idea where 50k went (and it's more than that with the money from his parents).
My ex used to get money from his mother, who would not have it to give, and still does, in his 50s. For his holidays & to buy a new car, that kind of stuff. Just horrible.