My Little Girl Is Gone...

After nearly 20 years my little Quaker parrot Lady Macbeth was my littlest daughter. We raced an hour and a half to get her to a hospital at midnight Saturday when I realized she was wheezing. I cannot believe I did not realize she was ill. I heard an odd sound 3 days ago but she seemed happy and healthy, playing peekaboo and whistling her songs. I let them take her back to put in an oxygen chamber and in less than 5 minutes I was told she was gone! I can't stop the what-if tape, and how oh how does one deal with so much hurt? I am absolutely devastated and wracked with guilt. 5 hours is just not enough time to say goodbye forever! So much guilt, so much pain. What to do? I just feel so lost....