(hug)I'm so sorry, St. Pete. I had a cat die when she was spayed at 6 months. It was shocking and awful. You are not overreacting at all! Give yourself lots of time to heal.
I'm so sorry to hear your news, stpete. Our pets love us unconditionally, and when we lose them, the hole in our hearts is agonizing. Sending you hugs and good thoughts.