(1) Discuss ground rules for interaction: no grilling each other, understanding that you will both have your own private lives and that you will each respect that privacy, safe-sex non-negotiable.
(2) Handle the business in a businesslike manner. Discuss how resources will be shared. This is the first step that needs to be taken to figure out what the options are. Going with the status quo where you save and he spends will really put you at a disadvantage if you ever D. You will have savings, he will have debt. You will have demonstrated that you can make do with less and still save, while he will have shown that he needs more resources. At the same time, really try to find compromises. A quote from my mediator might be helpful here: "Unless you both feel like you are getting screwed, it probably isn't a fair deal." This seems to be unfortunate, but true.