Supporting boyfriend?

My bf wants to get married by September. I am a little concerned and don't know how to ask about his financial situation with his ex wife. They have 2 children. I know he pays a substantial amount of child support and alimony that totals 50% of his annual income after taxes. However, I just found out on top of that he still shares a bank account with her and pays for her car payment, car insurance, credit cards, etc. I have a great job and am financially independent. However, I am virtually supporting (I know its my choice) him--he lives with me rent free; no utilities; no food; I pay for dinners out and any trips we take. I felt badly he was paying so much until I learned he is paying above and beyond the mediated agreement. Advice?