Oh, Jenn, I am so sorry that the news wasn't better. I will be thinking of you today during this difficult time (and in the upcoming weeks). It is the hardest thing you can ever do. By easing her pain, you bring it onto yourself.
Know that your heart breaks so that Mandy can take a piece of it to the Rainbow Bridge with her. Godspeed sweet Mandy. Be at peace sweet girl.
If you need to talk, I'm here for you.