Called Mom yesterday. Told her that we had thought it over, and that this was a weekend that my husband was going to have to take off work anyway, so we were going to use it for our limited vacation time and actually take a vacation. Mom says she's decided that she's going to visit my cousin in New York instead and that because we won't be available this single weekend out of the year, she's not going to be able to visit us at all this year. Then she brings up once again that she ONLY gets TWO WEEKS of vacation.
I suggested that she was welcome at any time to spend any of that two weeks with us instead of going to the island, but that we also only got two weeks and we didn't want to stay home for all of it. She accused me then of trying to make her feel bad. I said that I wasn't trying to make her feel anything, but the facts were that this was a matter of her priorities and choices. She started yelling at me, and I said, "This is getting ugly. I'm going to hang up now." And I hung up.
I actually don't think you did a good job (except for how you hung up--that was good!)
Don't go into such detail. Just say, "Oh well, that's too bad. Let us know if you can find time to come after all. The earlier you decide, the more likely that we'll be available."
Don't talk about her priorities and choices; don't lecture.
Stick ONLY to the facts. That's the *point* of the cut-and-paste technique. You *don't* argue, you don't talk about any underlying thing. You refuse, refuse, refuse to get into any other aspect of the entire conversation.
It's totally true that this is about her priorities--but it's also about yours, you know. Both of you have choices. You *could* choose to put your mom/grandmother first. You are choosing just as much as she is.
And you are also pressuring her, just as much as she is pressuring you. Perhaps it's in response to her initial pressure, but "she started it" is not a good place to be.
However, it's dangerous and potentially rude to talk about these issues in such detail. When it has been proven that this cannot be a productive conversation (which is the case for you), then you simply stick to the ONLY aspect of it that is important.
"That's too bad; we won't be available then. Let us know when you'd like to try again."
No other thing. Period. When she says, "that means that I won't see you for a whole year" in a guilt-inducing tone, the smart thing is to simply say, "That's too bad. Let us know when you'd like to try again."