I disagree with calling yourself and the kids casualties of this sitch. It's not the end of the world. Hurts, sucks, bites.. yes, yes, yes! But you can/will overcome this and come out stronger. I believe your kids can as well. It's up to you. Focus on what you can do...
Show the GAL how you care for your children, positive chances for yourself and the kids... but show, don't tell.