Hey MissFadu,
If your relationship is progressing to the point where marriage is being considered, I would seriously give your SO a trial run. By 'trial run' I mean (if you haven't already) maybe have a conversation about how his spending and lack of saving and increased drinking is scaring you/giving you second thoughts. He obviously loves you but I would just see if he is strong enough to actually do something about the situation and take action (whether that's distancing himself financially from his family and putting his foot down; drinking less; or both). I wish you both luck!!! The other ladies gave excellent advice and it's something I think about as well.
Cc
ETA: I also read the part where you said His issues are stressing YOU out. I know relationships aren't going to be a bed of roses all the time, but at this stage (you two are dating, not engaged or married), he should be uplifting you. Ask yourself what he is bringing to the relationship and if he is reciprocating. Just food for thought.