NCB, You are right, she is an alien, as many of our spouses are.
Here are my thoughts. I think what you counselor suggested about the wedding trip is excellent. I would not have thought of something like that on my own. Not only is it fair, it also lets her know that they are not "just" her children. If she chooses to continue this, there will be lots of compromise as far as the children go. She will not be able to just get up and go and do with children as she pleases. There will be several factors to consider such as whose weekend it is, etc. She needs to see this is not going to be a walk in the park. I think all of this can be done without hostility on your side. I know that is your goal to limit the hostility. We get so worried about their feelings that sometimes we overlook our own needs, actually let's change that sometimes to many times!
As far as the credit card problem goes, since you are an accountant I think you are in excellent position to divide the payments up fairly. I would explain it all in writing and give copy to her.
Take care and just keep praying. God will not let us down.
Life's challenges are not supposed to paralyze you, they're supposed to help you discover who you are. -- Bernice Johnson Reagon