That's awful OP, I'm so sorry your friend has let you down so badly and has turned out to be a complete bitch. I came on here having read your title to say something along the lines of giving her another chance etc because I know when my Dad died I had good friends who barely acknowledged it (I think it's true that most people just can't handle death and grief) but I am glad I didn't cut them out because 2 years on, I am still glad they are in my life, although I don't think I'd be going out of my way to support them in a way I think I would have done before.
However, this is a world away from barely acknowledging it because she is uncomfortable or whatever, she sounds totally self obsessed. I would be seriously considering something like Arf suggests - maybe something a long the lines of that while you understand it's disappointing that 4 people cancelled on her, but that she'd have to be a cold hearted bitch to think that of only herself when you cancelled on her for the reason you did and you'd appreciate not being put in a bracket with others as "cancelling at the last min" when you had genuine, heart breaking reasons for cancelling. Tell her it's bad enough that she doesn't even acknowledge such a devastating event in your life but the fact she is trying to make you feel guilty makes her a truly horrible friend. The week my Dad died I was due to go on holiday with my friends, some of whom live abroad and I hadn't seen in ages, of course I fucking cancelled & if they had dared said anything about themselves being put out, they wouldn't be friends of mine anymore.
If, after this, she apologies and maybe shows a bit of bloody empathy, I'd probably be willing to forgive her if it's out of character (like i say I have moved on from feeling disappointed with certain friends) but otherwise, yeah, she's not a friend, and to be honest, doesn't sound like she'd be a loss to you.
I'm sorry about your Dad 