Oh, I'm so sorry! It is always so heartbreaking to have to put an animal down. We had to make that decision with out dog when he got hit by a car and even though he could have had his leg amputated, he didn't have much of a chance of survival and even if he had survived he would not have enjoyed life the same missing a leg.
I'll be thinking about you tomorrow. Remember she won't be in pain anymore and she can just rest in peace.