I’m so very sorry that your family has been hit so hard twice. There is no good time to lose a parent. But before we get to our 20s, it’s especially hard. You still need their love, support and guidance. Instead, you are having to step up into adulthood and think about how to love, support and guide them.
By all means, talk with your sisters. You and your siblings are each other’s best support through this hard time. It’s far better to be sad and angry and confused together than to be each in your own corner, managing it alone.
You and your sibs should also be talking to both of your parents about practical matters like what their wishes are for the end of life. What medical interventions do they want or not want? They may not be able to tell you when the time comes.
Equally important is to talk about such things as finances, insurance and their wills. If you leave it until the last minute, they may not be competent enough to make the decisions they need to make. Further, you may be left with unexpected expenses or losing your home.
It would be terrible if your hesitation about doing such things now results in a major falling out with the rest of the family over medical decisions, funeral arrangements, bills and inheritance of property. It will be bad enough to lose your parents without also “losing” the rest of the family because no one was willing to swallow hard and do the things that needed to be done.
There is no way to make this easy. But there are ways to make it easier. Preplanning and communication will ease you all.
I wish you well.