Putting down a beloved animal is one of the worst experiences in life.

I'm always hesitant to recommend books on such a personal subject as loss of an animal, but I used to have about ten of them and I got rid of all of them except for "Pet Loss: A Spiritual Guide" by Eleanor Harris. Some of those books are terrible. But that book hit the spot. But it's very subjective trying to figure out what is a good book for someone else. I even got some comfort from a children's book about losing an animal.

A newer book about grief in general might be good too. I think we've learned a lot about grief over the past few years. I remember a time where people didn't take grief over losing a beloved animal seriously.

One thing you read over and over again is that there is no such thing as a "wrong" response to losing someone, and to be easy on yourself and not judge what you are feeling.

Just googling "When grief manifests as anger" turns up a lot of interesting looking articles. Just be careful because there is some incredible crap on the internet too.

What Is Anger? A Common Manifestation of Grief

https://thegrieftoolbox.com/article/what-anger-common-manifestation-grief