Heather, I'm going to be perfectly honest w/you, the question he asked your daughter about her going to work w/you isn't innocent, he's digging for info and is trying to find out exactly what your d12 is doing. He is trying to find out if her homeschooling is structured, if you are devoting the necessary time required for her homeschooling or she's just doing whatever she wants.
I do think he truly loves is girls, but he doesn't know how to relate to them because he's not been a permanent fixture in their lives for a number of years. As for calling her by the nickname his family insists on using, it tells me that he's been talking to them about your daughter. Not to scare you or give you an additional worry, but you don't know what he and his family have come up w/in regards to D12. Don't be too sure about the custody request. You haven't gotten everything out on the table yet. I don't trust none of them at this point.
I'm glad your mother is spending Thanksgiving w/someone. I hate to see people be alone on holidays. I know you don't like your stepdad, but if he's making her happy right this minute, that's all that matters. At least she's not crossing over on to your street today and getting in your business.
Any way, take some time out and pamper yourself this afternoon. You've had a really tough week all the way around. Hopefully tomorrow will be better as it is TGIF!
Take care.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.