I'm pretty sure it's the fact that it would give her time with an AP versus her pushing the kids off on you that is bothering you.
It's important to recognize what we are really upset about so we can set our perspective. You can look at is an opportunity for her continue on with the affair.. or an opportunity for YOU to spend more time with you kids. Your children are not pawns... They will remember who fought for them when they are older.
You hit the nail on the head. This has come up before on these boards 3 years ago post BD1 when she did the same thing. If I look at my values, which is wanting maximum kid time, then I shouldn't give a F about her motivations, I get what I want.