Yowza. Good luck with that, Lydia. My mom's here, and as much as she's great to have around, I find myself having to "pull her up" in terms of her behavior around Oscar. She and my sister who's visiting too (25, who lives with my mom) act like *****y old women with each other and snipe at each other. I hate it, can't stand the aggressive tone, and refuse to allow it in my home. So twice already I've had to say "cool it, that's not okay in this house" and I feel like a total *****, but I refuse to let Oscar learn that it's okay to treat people you love with disdain. I had to unlearn it and it wasn't easy (or fair to my husband).
Anyway, sorry about your dad-stress. I sure understand. and even though he's paying for preschool, it's still okay to be annoyed!