That's awful. I can't understand someone going to the bother of conveying that invitation to you, with no intention of following through. It's possible something might have come up, though that doesn't excuse your cousin. Try calling her and asking if she would still like to get together. Don't text, but call . . . so you hear her voice. If she sounds like she wants to wiggle out of her offer, then you'll have confirmation that she was insincere when she made it. On the other hand a lot of people say things they really mean, but don't have a plan to follow. Your cousin may need help in deciding the when and the where. I'ld give her another chance.

As far as your friend not wanting to go to the office reunion: I can see anyone not really wanting to go back to a place where they no longer work. It can feel kind of strange.

It does sound like you need to recruit some better friends. You need friends to have any kind of a normal life. Someone you see once a year isn't a "good" friend, unless there is some big geographical distance between you.