I am going to try and take a stab at your cake-eating question. IF you feel like a doormat then set your own boundaries. You can catch more flies with sugar then vinegar. The goal is to regain her trust and become her friend. I personally found that being nice to my H was much better all around. There will be times when she will bait you into a fight just to see if you are "real" but don't fall for it and keep being the kind loving Husband. She needs to know that you are there for her even if she is acting like a stupid teenager at times. She will keep looking back to make sure you are there. It is not for you to punish her or make her feel bad. This will take every single ounce of self control you can muster. You are her Husband not her Daddy. Unfortunately at this time you need to give her all of the freedom she can choke on and let her figure things out for herself. Hang in there, it is a long, hard journey but you will get to the other end.
There can be no testimony without a test. I am praying to go through this test and come out the other end with a new and better marriage then before.