Well, I'm sorry about the way it turned out.
All I can say in their defense is that it's so easy to have high hopes and over-extend yourself when you are traveling and trying to cram in as many things as possible over a short time.
Last time my sister and I flew back east, in the span of a week, we had a memorial for our dad, attended a family reunion, found out we were invited to a very formal family wedding that we hadn't packed appropriately for, we had relatives that wanted us at their house, we visited all the family cemeteries. We were stretched so thin for time and still didn't get to do everything we'd hoped to. We didn't fail to make any appearances, but we were so rushed the entire time, we barely slowed down enough to just really enjoy everyone. We didn't have our own rental car, so we were driven here and there and kind of at the mercy of our relatives doing the driving.
We had a wonderful time, don't get me wrong...I'm just saying I know how it can be when you have so much to try to do.
It certainly would have been right for your friends to make an appearance after all the trouble you went to. Waiting until the last minute to call off wasn't nice at all. Yes, frankly, it was rude. However, I do wonder if their goals were a little too lofty and they said, "Hey! We're coming! We'd love to have a get together and see everyone!" You took that to mean it was definite, they might have taken it to mean they really DID want to get together and see everyone, and ultimately, it just didn't work out.
I'm really sorry for the way it went. I think you can forgive your friends and know that next time, nothing can really be carved in stone with someone who is trying to cram so many things in.
Just my opinion.
You do have a right to be mad, but hopefully, you can let it go.
Best wishes.