Can I change my direct deposit without getting in trouble?

We have filed no papers. We have a joint checking and savings account. My checks are direct deposited. My wife has increased her credit card spending to nearly 4/5 of my monthly salary over the last 2 or 3 months and extracted savings account money to try and cover her bills while paying just barely minimum to my single credit card (she has about 6 cards). The money she took out of savings was to pay property tax due at the end of the year. I am concerned with her expenditures and how she will pay for needs of our children. If I move my direct deposit to a new account that she has no access to, am I looking for trouble? I am fine with paying bills but must get preservw capital or we will all go down. Will I be overstepping by opening my own account and moving my direct deposit there?

No, you are within your rights to do so, and I would recommend you do.