The best thing you can do is listen to your gut. It is easier to walk away from a bad relationship than it is to destroy a marriage, especially after you've had children.
Stand up for yourself, and tell her she is not the one. You cannot change her. You cannot control her. You can only control yourself. Don't start out getting married to the wrong person. There is nothing wrong with realizing that she is not the one.
Stop now, before you get in deeper.