Until you decide re:filing Sep ... you can and shoul consider individual checking and credit "so you don't have to see how much he spent on your roses" and he doesn't have to worry about what you are spending on food.
Make arrangements for him to deposit a set amount into your separate household checking each month. If you don't already have a detailed running budget plan begin making one. Pull as many historical records as you can.
Utility bills charges for groceries medical insurance etc
Build a detailed budget. You need this to support financials in a Sep or other.
If he will adhere to your financial needs you will have funds for living. If he does not go buy two Porsches, you won't owe for half of each. That is the trick. Do you trust him to live solely on the monthly amount you two agree to for his checking?
The Sep is to provide that kind of protection. Expensive but worth it if you believe the risk is great enough. As you pointed out, the risk is also that it may anger him into filing his own action. How reasonable do you believe him to be?
Cake eating is handled many ways. Dobson folks say tough love. Others say be friends and do what friends might do so one day it is easier for him to decide to come home to his friend. I say with a MLCer it is often impossible to do so for long. As a friend you are likely to find out more details of his life than you will want to know. How strong do you believe yourself to be?
