Tips to cope with stress?

My fiancé doesn't know how to manage money and consistently spends instead of saves and uses money he doesn't have. I'm constantly talking to him about it but it's like talking now to a wall. He doesn't listen. I thought that he would straighten up now that I'm pregnant but he's still not listening. His younger brother manages finances better than him. I've never dated someone who did not care this much before. I'm so stressed and constantly crying because I cannot figure out how to get through to him. I need help on coping with this. I'm tired of worrying.