Took me a while to have the guts to solve this one, but it is doable.

Separate accounts. My paycheck goes into my account. Then her allowance gets transferred from mine into hers. So she cannot pull more out of my account than we have agreed.

As for credit cards, you cannot stop her from opening them. But when I was most desperate, I got her to agree to put a fraud alert on her credit file. That means the credit reporting companies send a letter every time she opens a new account. And I had her list my office as the place where the letters go. So while I cannot stop her from opening new accounts, I can see them fairly quickly. Since the fraud alert got posted, I don't think she has opened any new accounts. Gee, I guess opening new accounts isn't so much fun when you have to pay the balances back yourself!

Oh, and I keep my checkbook in the credenza in my office. So no more stealing checks and forging my name to pay off credit cards.

So a combination of separate accounts, fraud alert, and keeping all papers in my office has worked fairly well to cut down the overspending. Every so often she still finds a way to do an end run. A couple of times she asked to borrow my card so she could buy something online for one of our kids. She had the web site save the credit card information, so she could go back online later and order more stuff. I had to sit her down and delete the information from the web sites. For a while, I slept with my wallet in a locked drawer. For a while I slept with it under my pillow. But lately it has been safe for me to put it on my dresser at night. She doesn't get up in the middle of the night and use the cards online. At least not so far as I can tell, and I do make sure to review carefully every monthly statement to make sure there are no unexpected charges.

As I said to Hitchhiker, I can't imagine why I don't feel safe around her.