My main character is supposed to have a mental breakdown in my book and I've been brainstorming ideas of what could trigger it. To paint a bit of a picture, he's a total loner and has been all his life. He lives with his older brother due to their parents being in jail, and his older brother is an awful person. He's always abused my main character as a way of obtaining power he never had in his life. Because of this, my main character is already a little unstable. One thing that he's always had was his dog. He finds socialization to be difficult so he's always preferred being around animals. This is shown a lot through the book. He takes care of the animals on the farm he lives on, he's always with his dog, as a kid the dog was his only companion, etc. One day, the older brother goes a little too far with his abuse of my main character and the dog attacks him. After the attack, the brother shoots the dog and forces my main character to witness it. For a few days, my main character is in shock and eventually that all builds up to him having a mental breakdown and trying to kill his brother. Do you think it's too far fetched of an idea? I just want to make sure it seems reasonable for someone to lose it that badly because of something so cruel happening to a pet rather than another human. Thanks for the advice!