Sorry, OT, but I have to disagree with you on a few points. Perhaps clarifying things will help.
I am aware that I no longer have a relationship with exH beyond co-parenting--and even that is limited by his apparent need for me to be invisible and just go along with all he feels entitled to. (Sorry, no longer married--don't have to go along!) I'm also aware that HIS family is HIS family--even though I was a part of that family for 20 years and have no relatives of my own. If they choose to end their contact with me--because they've heard no end of lies about me--that's their business, and his.
My concern here is not for my own feelings, but those of D13. She has expressed great discomfort about spending the day with the woman--to the point of having anxiety attacks. I don't--nor have I ever--probed for information, guilted her, or done anything to undermine her relationship with her father. She figured out--probably even before I did--that her father left for someone else. He has handled integrating that relationship into his relationship with his daughter very poorly--he had them meet on a spur-of-the-moment whim, without any preparation. She feels pressured to have relationships with her and her adult children, and he's been rather insensitive about prioritizing his own daughter--she feels like a runner-up in his heart to her daughters and grandson. These are all feelings she has poured out through tears. We have informal and flexible arrangements for holidays, mostly so that D13 can spend time with her cousins; she's with exH more on holidays than with me. So while this is "his" holiday, it's her wish to split it with me, rather than spending it with the OW (so what do you propose I call her now?) and her family. There's apparently a lot of tension between exH and his future MIL; D13 expressed that she didn't want to be "all nervous and waiting for another blow-up" on the holiday.
There would be no drama, no jerking-around. The plan is for D to call me when she's ready to come home; I would pick her up in the driveway, quietly. She has felt free to spend the whole day with her father, but she feels a distant second to OW and family when they are all together--she doesn't want to spend it with them.
Believe me, OT, if the past 18 months have taught me anything, it's that I'm entitled to nothing. ExH, on the other hand, has expressed that he feels entitled to have his "whole family" together whenever he wants it, without much regard to how that might impact his D. I grew up forced to live with the OM who came between my parents, to treat him as a father even tho he was an abusive alcoholic; I was told to "just get over it" because this was now my life. I refuse to shut my daughter's feelings down in the same way. I know how this feels to her, and it's not about my victimhood at all.
M60 H52 D20 M14 yrs OW-old gf from 1986 bomb-5/18/08 H filed for D-9/10/08 D final 4/24/09 xH remarried (not OW) 2012