Take time to yourself and breathe. Think through all of this and make a clear headed decision on what you want to do next, and if it's worth it to even try.
Regardless of what you decide about whether you want to try and save this, the action is the same. No contact, detach, PMA, and STFU.
Remember, your actions and words from here on "can and will be used against you in a court of law". Everything you do, and the decisions you make should be for you and your children's future.
This is tough. I'm right there with you. Talk to an attorney, and educate yourself on the legal process, regardless of which way you eventually go.
You can't change her, but it's time to start driving the car/steering the ship.
