Is this a boundary you can actually set and maintain?
Don't give an ultimatum unless you can back it up 1000%
What's the goal? To save your marriage? To protect your children and your assets? Are these goals mutually exclusive right now, given the reality of the situation?
One thing you don't acknowledge that I think you need to pay attention to is this: your marriage, as you knew it, is over.
Let that sink in.
If it was working, you wouldn't be here right now, so ... that's not a bad thing, for a dysfunctional situation to be over.
Look around for what's really left and build from there. Focus on yourself, your kids, your GAL. The fastest way to have a new relationship with your wife is to let her go. Read that again. You need to build a NEW relationship with your wife.
Is she someone right now with whom you'd want to build a new relationship?
I realize this is harsh and I'm sorry, but it's the truth. Don't try to win her back. You won't. Not in the way you want. Do you want someone who says I love you and sends hundreds of texts to some random dude she just met who is paying her attention and letting her not focus on her own recovery? What does a person who is doing that have to offer you or your children?
This is a very broken woman who needs to find her own way right now. And the truth is, you need to find yours as well. You're ripping through the steps at a ferocious pace, but I wonder, are you really digging deep, especially the steps you're working on ... Do you honestly feel that you gave enough time to the real core of steps 6 & 7? It's more than a surface writing and working with a sponsor; it's a new way of life. It's not a race, like if you get through all 12 at breakneck speed your marriage will suddenly be intact and great again. Really look at your motives and your expectations. Expectations have a nasty way of coming back to bite us in the @$$.
Focus on what you want, and who you want to be. Be the most amazing person you can be, someone only a fool would leave. Focus on how to protect that little 6 year old who's witnessed his mother ranting and raving like a crazy person and burning things in her rage.
Your best shot to save your marriage is to surrender and hopefully down the road build something stronger together, after she's had a chance to work on herself and you've had a chance to do the same.
Priority one should be talking to a lawyer to find out what your rights are, how you can protect your children and yourself.
Don't issue any ultimatums until you know where you stand legally.
In fact, don't issue ultimatums at all. That will blow up in your face just as badly as the cutting off of the credit cards did.
There is a difference between ultimatums and boundaries. Find that difference.
