I agree with Shirley. If this is not an unusual thing for them to do, then Chris, you just deserve better friends–no matter how much you love them. Maybe you could explain that you won’t let that happen again (i.e., what SU said–don’t volunteer or plan anything), that they owe you big, big time, and if it happens again, goodbye. And mean it. (Or, end it now.) BTW, it’s completely natural to want to cry in addition to wanting to kill them. They were very dismissive, rude, inconsiderate, and overall unloving as friends–and that hurts. And not to be redundant, but you deserve better than that.
I, on the other hand, want to know how to end a friendship with a dipshit. My friend (the one I once had a thread about her asking to borrow money) is revealing herself to be the kind of person I just don’t think is good to be around. She makes very stupid mistakes on a nearly daily basis, but is so ignorant about it as to be arrogant. She simply does not get it. She just called the other day–fishing for money because her car died. Then she fished for a ride to various places. I hate it, because I really want to help–but she creates these problems herself, and doesn’t learn from them. I say “No” as indirectly as I can ecah time. 
She also doesn’t listen to anyone telling her she’s screwing up.
She’s now dating someone who has inordinate sums of money at a very young age, but will tell her nothing about where it comes from. All he tells her is he runs his own business; it does seem a bit suspicious. Now, it could be any variety of thing, but knowing her, it could easily be some sort of drug or weapon smuggler (she’s honestly a bit too slow to figure that out). She hates him, but openly says she’s using him for money. UGH. (Even if his money is legit, the potential remains in her to make a big mess of her life.) She could get herself into all kinds of problems, and I’m starting to think I should remove myself for my own protection.
A question that would relate to both Chris and myself–how do you end a relationship with a dipshit? Do you TELL them they’re a dipshit? Do you just fade away? Do you try to help them by explaining why the friendship needs to end?