Preventing abandonment


I am currently in a relationship that involves two sets of children mine from previous marriage, and ours. My spouse, IMHO, is too strict on my children but not strict enough on our children, and she belittles me at every possible opportunity. I have been putting up with this treatment for some time now and have had it. We have discussed this on multiple occasions and nothing changes. I have taken steps to acquire a place to move with my children from the prior marriage. My understanding is that in order to keep from getting hit with abandonment, I need to start working with my spouse to create separation agreement prior to leaving. What other steps should I take to ensure I don’t get hit with abandonment?