Hi Mepicurious - oh man, not you too on the Thanksgiving mess. I'm so sorry. With the exception that my H isn't directly saying he loves the OW, I can truly say I know your situation really well right now.
Stay firm on the "NO" about spending it with him - but it is going to force you to make a choice. If you firmly say "NO" and trust her enough that he won't show up, you can hope for the best. I'd still have an escape plan in case he does show up though. That's the route that I'm taking right now. I'm working on a calm but firm "script" and will be sure the car's parked where I can get out if I need to. I'm still debating on putting dishes and stuff in the car so my side of the family could take our dinner to the park or something.
If she's really pushing or you don't trust her to tell him no - who's supposed to be coming over to your house for Thanksgiving? If it's your family too, I'd make other plans to spend it with them. Maybe you can all go out to a nice dinner or go to someone else's house or something. That way you're not stuck in a miserable situation but you won't be alone for the holiday. If that does happen keep in mind it's up to you if you want to tell them what's going on or not - you can find a vague reason that you're spending the holiday apart if need be (i.e. she's not feeling well or not up for having a big crowd over or something). And keep in mind it will put her in the situation of having to explain her bizarre behavior to her family. It will be very awkward, and you can always hope that some of them will talk some sense into her.
I'm so sorry she's doing this to you. It hurts so deeply - I didn't even know I could BE hurt the way this particular thing hurts me. Be strong.
Me 35, H 38; Together 13.5 yrs, M 7 Bomb 1 10/07/06 Sep'd 1/14/07 - 4/15 Piecing: 4/07 - 9/07 Bomb 3 10/11/07: Never loved you, let's separate 2/08 slowly improving 7/08 Piecing (7/25/08 rings back on!!) Current thread