That happened to me when I was right about at the stage of divorce/child custody/Alcoholic Decompensation that you are. I wept and wept and a woman I knew from town but wasn't really close to saw me at the vet's office and said "oh honey, it isn't really about the dog, is it?" and I thought "But I LOVED that dog."
The alcoholism and my divorce just really opened me up to all kinds of sadness and loss and made every setback so much harder to deal with.
My cat died this summer and I had a terrible time with that, too.
I'm sorry. Why do all the sweet creatures have to grow old and die while those who cause us misery go right on??
((hugs))