I think you want to be divorced. At least that is what I get from your posts.
My boys were 12 years old when their dad took up with his former OW. The D impacted them and it continues to this day. Thank goodness I have a daughter who tells me things! I know that WA's have no idea how their actions impact their kids (nor do they care), but thank God someone is left behind to know. I think that's our job FL. It's the most important thing we will ever do. To let our kids know that we know what they're feeling, even if we say nothing. Sometimes I think they only want to have a home, a parent to let them know they care, a parent who cares about them...
I've written you before to tell you that it's the kids who need us. This is still true. Mine are 19 and they still need me. Divorce sucks. But I had them and I love them. They did not marry their dad. They did not ask for a D. And they know that I love them so they are happy. To an extent.
Whatever happens with gym woman happens. The most important people in your life right now are the kids that you and your STBX had together.