I got to your post a little late but felt obliged to reach out and *hopefully* give you some perspective.
I am truly sorry for your struggles, sickness and deaths are huge trials for any family to endure. But don't exacerbate your troubles. Her wedding is a momentous occassion and should be a silver lining in all that's going on in your lives... it's something your family can look forward to. A chance to celebrate life, love, family, etc. I suppose I can see how you and your other daughter are hurt by her choices. I can't say I wouldn't have been hurt had I not been my sister's MOH. But nonetheless, she made her decisions and you guys have to roll with the punches. Look forward to the occassion as it's a special day in her life and a chance for you all to let loose, forget your worries, and have fun, even if it's just for a day.
I'm additionally sorry if you felt attacked by the other women on this board. They most certainly do NOT mince words. I've been offended at times here. But after I sleep on it, I appreciate their brutal honesty and the opportunity to see things from someone else's perspective. Let it be a lesson learned that you shouldn't come here strictly for validation. Furthermore, if you do not hear what you want, don't strike back. It just fuels the fire. That said, even though I don't agree with the way you handled the criticism, I do feel bad for you and will send some prayers your way. People deal with hardships in different ways... I assume you are extra-sensitive given your circumstances and perhaps that's played a role in how you are handling your current situation with your daughters, and your response to the feedback you recieved here.
In situations like this you need to know you can not control other people's choices/behaviors/attitudes. All you can control is how you choose to respond. And part of that process is determining which response affects you the LEAST. You have an obligation to yourself and you are resposible for your own happiness. If you don't like your daughter's choices, don't talk about it. Not with your mother, your other daughter, your husband, etc. For your own sake, you have to leave it alone.
Wishing you the best of luck and hope you and your daughters enjoy the special day that is coming up!