Guilty or to not feel guilty

I have a dilemma at work that is robbing me of my sanity and making me feel like a shit for no reason. Here's the backstory:

The staff of my store was asked to submit vacation requests for the 2009 calendar year. I'd turned mine in to my Store Manager almost 2 days after the request. (I'd forgotten to do it, mea culpa.)

The schedule comes out yesterday and another manager (Dorothy) says to me, "I need your week off."

"Why," actually..."No, why?"

(laughs) "C'mon Joe...I need your week. A friend of mine is having a kidney transplant and I need to be there. I put in my request for the week before you and she called me today to tell me when her surgery was gonna be. Your week."

"I wish I could help you, but the vacation we have is the only week hubby has in the Spring without meetings or training."

This exchange has happened three times since the first conversation, each additional conversation getting more and more like emotional blackmail "My vacation is more important than yours," "You should want to help her," " do the RIGHT thing."

I'm just worn out over the whole thing. on one hand, I would trade the holiday/vacation in a heartbeat because I normally am a sucker for that, but this time Jack only has this one week available between now and, like, May to take a vacation that he sorely needs.

I get that this person is giving a kidney to save her husband's life. I do. What I don't get is the importance that my coworker is putting on her being there. This person isn't family and has family (I assume) to help. my coworker had already put in for vacation the week prior to mine and had no idea when the surgery was planned. It's not an IMPOSSIBLE situation, but one I don't feel beholden to repair. And somehow I know I'll feel guilty about it, regardless...