Like I said, I will be with him and his kids on Thanksgiving at his parents. I just heard back from my sister-in-law (about an hour ago) that they are hosting Thanksgiving for my family on the Sunday after Thanksgiving. They've already met C, so she also made sure that I knew that he was invited as well.
What I just did was sent him an email about the plans for that Sunday with my family. I also mentioned in that email that if his kids are with him on that day, and IF he and his kids felt comfortable with it, that they are invited as well. I have a feeling that this might not be a comfortable situation for him and his kids, in that his kids would then be meeting my entire family, but I put it out there. I really did not want to email him about the plans, as I would rather talk to him about it, but on the flip side, I also wanted to give him some time and space to think about it without him feeling pressured to give me an immediate answer. I feel like I took the chicken way out, but like I said, his knee jerk reaction would probably be to say no, thinking that he would have to give me an answer right away. It is my hope that he will be able to think about it, talk to his kids about it and then come back to me with his answer.
All I can do now is just wait for his reply. If he does not respond to me via email, then I'm sure that we will be talking about it tonight when he calls.