Deb, I've been there, and was invited, uninvited, "Crazybook" was involved and ultimately I did not attend the wedding because I wasn't invited. I also had an alcoholic ex-husband who I'm told has told my son lies about me that would have had me in sitting in the dock with the Gestapo during the war crimes trial. Since he lived with me for a couple of decades I would have thought that all the good things that I did for him would have given him at least a few decent memories.
This is a swamp, and IMHO, you'll be scapegoated for the next 2,5,15 years (or months) as long as their marriage lasts.
I would unfriend all of them with the phrase "I think it's better that the younger generation spend time on Facebook with people their own age".
I would cut off any financial aid and do what your doing, letting God take the lead, however, God helps those who help themselves and I would plan for a trip or spa day/week in the event that you are not invited to the wedding. I spent the day quietly in the company of some close friends, have never looked on anyone's Facebook page, so haven't seen any wedding photos and am no longer in touch with my son.
Never in my wildest nightmares did I ever imagine during all those years of taking care of him day in and day out that his wedding day would come and go and I would be banished from a place of pride there.
It's been quite a few decades since I married, and in those days families ties and expectations were stronger, with invitations mandated to be sent to someone's third cousin that you hadn't see in decades.
Remember this isn't about you, except that IMHO you are unfortunately stuck in the scapegoat role and 2 against 1 isn't an easy spot to be in.
There's no bulls eye on my back, but as someone who has lived through what you might have to I would have Plan B ready, and I wouldn't tolerate the "invited, not invited", this isn't a game of "She loves me, she loves me not" that we used to play with daisies.
I would sit them both down and tell them that you are considering whether or not you are prepared to consider attending the wedding after being treated in such a badly mannered way. They will likely revolt and tell you to take a hike, but I'll bet you $$ to donuts that will happen in the end anyway.
Always deal from a position of strength, and if they can't accord you a minimum of courtesy, getting whipsawed for the next few months with the invitation being dangled as a carrot on a stick is only going to make it worse and if you aren't invited, send them a donkey as a wedding gift with a basket of carrots. (Wish I had thought of that earlier and done it myself).
Take care, be good to yourself, and find as much solace as possible that your active mothering role is over and it's time to move on and find as much joy, happiness, laughter and delight in your life that you can grab with both hands.