OK, I have been slower than I planned. I'm trying to figure out the money. In other words, I can't figure out how to pay for a place to stay right now. It's only math, I will figure that out.
Should I move out right before OM shows up? He's coming the first week of August. Would I not just be sealing the deal for her at that point?
I would not move out right away. It just makes you look like a scaredy cat running away from the OM. F@ck that! I would stay put in the house.
Meanwhile, you can start exploring some living arrangement options. Looking at places takes time along with considerations for your kids...meaning access to your children and financial feasibility.
Even if it means you start saving up for a move in September for down payment and other practicalities.
Do not do anything hasty.
When you have all of those details lined up, then you can casually tell your W that this isn't working out for you and that you're moving out on XXXX date.