Very sorry to hear about your daughter. Our twins were born at 32 weeks, but we lived in fear from week 28 on when diagnosed with PE. Don't let it break you heart when you look at her. Let it fill you with hope, because your daughter is still alive. You don't say how much she weighed at birth, but do keep in mind that on average at 26 weeks there is a better than 85% - 90% chance of survival. It is almost certain your daughter will live, especially if you were given steroids at least 48 hours before birth. And, as JacobKaden says, it is well known that girls mature faster than boys at this age, so you have that going for you as well.
Let the doctors take care of the little things like keeping her alive. Your job is to concentrate on the big things, like giving her the love she needs to keep going. Every day your daughter is alive, she grows just a little bit stronger. It may seem inconceivable now, but in 8 weeks or so when she is ready to go home, you are going to feel like a miracle occurred.
I won't say this gets easier, but I will say that unless your doctor says otherwise, it is highly likely that your daughter is going to make it. Despite the fear we all have as parents, almost all of them do. That little bundle of cells is much stronger than you think, and her optimal survival strategy depends on you being there for her every step of the way. Without fear.
You can do something for her. You can love her. That is what she needs most from you. Don't underestimate how important that is.