You waited till NOW to tell me?

So. We have had a few continuing sagas here at chez OHN. I will touch upon one today. FDIL (future-daughter-in-law) called me to ask my opinion about an issue she is upset about. We get along great and in fact she is usually the one pushing S1 to come to our home for the weekend to eat all our food visit. She has a somewhat complicated relationship with her family. She is very close with her paternal g-rents as she lived with them when her mom and dad split when she was in middle school. I haven't met mom, though have seen photos and she is stunning. Dad is HAWT. No two ways about it. His muscles have muscles, and he is styling. He oozes sex appeal and loves to be noticed. He walks with the gait of a man that knows people are looking. Sorry--- I digress.
So, here is the current issue. FDIL and S2 are keeping the wedding very small. Family only, on the beach, about 12 hours from here to keep the unwanteds away  keep it intimate. FDIL's mother has told FDIL and S2 that her good friend Sassy will be driving to the wedding with her and they are renting a place there for the week. At first I thought, oh, how nice. Then FDIL and S2 told me that Sassy is loud, obnoxious and they don't want her anywhere near the wedding. Hmmmm. So, they want her to drive 12 hours, rent a place for a week and then tell her she can't come to the wedding? Touchy. But sensing the vehemence of which FDIL and S2 can't stand this woman I told FDIL that she should be honest with her mom and tell her that just because mom is friends with Sassy, FDIL doesn't have to be, and even though mom feels like Sassy is family, she actually isn't and that BigD and I have many friends we consider family but we are abiding by the decision that the wedding is family only. Just giving her some things she can use to help her mom maybe understand.
FDIL thanked me (we had three or four convos about this subject) and I related my own invite/don't invite wedding nightmare story (for a later date) and she said it really helped.
Last night I am talking to S1 and asked if FDIL got it all straightned out with her mom and he said no. Well, I continued to tell him that it is THEIR wedding, neither stunning mom nor HAWT dad are paying a dime towards any of it so S1 and FDIL had every right to determine who gets an invite and who doesn't. Just my opinion. I wasn't telling them what to do, just answering their question.
THEN, S1 lands the BOOM. If I had this info at the beginning when the "what should we do" question was first posed my answer would likely have been different.
Apparently, though not openly discussed, it is highly suspected that stunning mom and Sassy are *more than friends*. Yep. Apparently when HAWT dad and stunning mom were divorced and dad moved out.....Sassy moved in..... and has been a continuous presence in their world. So after S1 dating FDIL for a couple years, getting engaged, and them spending countless weekends here eating all of our food  visiting, I am just hearing that his future MIL is probably g.ay. Honestly I don't care who loves who (or is it whom?), everyone deserves to be loved. I just can't believe that that teesy weensy detail was left out of the question posed to me about whether Sassy should be invited. Holy shit kids, yeah. If stunning mom is in a relationship then Sassy should be invited....just as HAWT dad's bitchy wife will be going. If in fact stunning mom is actually g.ay. She hasn't actually told her family, but everyone seems to believe it is so.
If she is...... she is not only NOT out of the closet, but the door is locked with a padlock.
This is beginning to sound like a S.pringer episode.