I agree with this. Knowing how much 2M with his agreement and his wife with her offers and following through of driving the kids have been accommodating, I don't really feel a need to question if 2M has danced on the head of a pin finely enough. And, it does look like they already considered other options.
2M, I know you still hold hostility toward Mom for the things she's done to the kids and may want to unload on her beyond the instant circumstance, but OG's suggested email is direct and to the point. I thought about maybe softening it, but the only want to often it is to remove that she can no longer communicate with your wife, but that's not the right thing to remove, either. She has boundary issues and had no right going off on your wife like that. Your wife already has anxiety issues and doesn't need this crap when she's only involved to do others favors so I co-sign OG's email 100%.