I think your question kind of says it all... How can you control his spending without appearing to control it? I don't think you can... I agree completely with you, by the way, so this is said with all love... But you can't really address it fairly as you point out you are not contributing... It sounds to me like you two better get some financial planning assistance, or counseling so that you are both on the same page... <br />
While I agree that you are affected and he had his priorities out of whack, it isn't going to change once it really IS your money too I doubt... <br />
Wish you the best of luck, all I could suggest is to just lay it out and be open about it... Money problems have a way of bubbling up, so best to just get it out of the way as soon as possible :-)
There is a very simple explanation: What yours is mine and mine is mine :~)
You two need to settle this monetary issue before you get married -- money is one of the major causes for pain and suffering in a marriage.