Just needing support

My family has been the sole caregiver for an aunt with stage 4 colon cancer the past three years. We've always known she's terminal, but she also has responded so well to her first line treatment that we always thought she had a bit more time. Last week, her abdomen because hugely distended, her intestines started bleeding, and her liver failing. She's been in the ICU for a week. She's regained consciousness which is great, but we still are facing a two week prognosis if they can't reverse it all. Obviously we're all heartbroken. I'm also getting married in two days. My family is coming to the wedding, but they've already told me they won't be happy. It's nothing against the groom or the marriage, they just don't feel happy right now. I feel like a spoiled brat because I'm so upset and have been crying because they can't find it in themselves to be happy at my wedding. They've assured me "I'm sure we'll smile." I feel so hurt. Of course I'm also devasted (the aunt is my godmother), but I also want to be happy at my wedding, and for my family to be happy. I can't shake the feeling that they must love her so much more than me, that the pain at losing her in the near future is so much greater than any joy from wedding now. Am I being selfish? Am I being a spoiled brat for thinking like this? I would have postponed the wedding but it would have meant adding a lot of money, plus I don't even know when to postpone it to, so it could end up being a year by the time we rebook a date (weddings are booming here). But I still feel so selfish and cruel to throw this on my family now. Thanks for listening, I just needed to let stuff out without burdening my family.