Oz, I didn't see this in time but I would actually have suggested that you ask her to be there, so I don't think you did anything wrong. I think it was really rude of her to refuse and blame it on work, but rudeness is definitely a well-worn tool in every WAS's toolbox. So don't feel stupid, you are at a very vulnerable moment and you could have used the support. It's unfortunate she can't help you at least as a friend, but it is what it is. Can anyone in your family come visit for a while? I took a week off and spent it with my dad when he was going through chemo and radiation, he needed support as well as help with basics.
By the way, I would absolutely write her out of your will. Not to be vindictive, but she clearly doesn't consider you two in a relationship anymore so your estate should go to someone who cares.
