I sure didn't have time to read more than a dozen posts to this thread, but this sounds like perhaps more of an issue with the specific person who made the invitation.

When I go on a regularly-scheduled ride for the first time, I always come fully-self-sufficient, and with just about no expectation as to whether I will be able to keep up and complete the ride or not.
Experience has taught me that the same applies even when invited by a rider who does the particular ride often.

It seems that after a while, riders show up to most regularly-scheduled rides with clear expectations as to speed/effort and distance/terrain, so I am very careful to not put myself in the position of having to ask for that to change.
I've attended rides where I regularly got dropped for many weeks until I could stay on board for the duration, and there was ultimately satisfaction and training benefit from that. I have known women who went through the exact same process in preparation for a season of long rides and/or racing.

But again, it sounds like the inviter perhaps failed to communicate fully, and then failed to show any concern for your fate on the ride. I am making assumptions there though, based on what I don't actually know about your ride history together, and on many other things.
I would advise to let someone (ride leader) know if you are uncomfortable with the idea of bailing on a ride and making it home in a self-sufficient and safe manner, which of course might depend a lot on the conditions, distance and geographic location of the route. I am not able to say whether or how badly that anyone failed in their responsibility here, as there are just to many things about your situation that I am unaware of, but at least you now have a better idea of what this group and their rides are all about. Thankfully you made it back safely, and I hope not too discouraged. Hopefully also, that you have other rides/groups to choose from.