yes, my father has been very calm and reasonable through out this. he wants what's best for my mom. he thinks that if he moves out for awhile he'll be able to see if he's the cause of my mom's problems. even when my mom completely makes up stuff and throws it at him, he doesn't bark back and he stays calm.
It sounds like your mom might be a little emotionally unstable, but you have to give her some excuse for not being calm during this. Your dad is the one who's breaking up so in a way she's a victim. I'm not saying your dad shouldn't divorce, but it doesn't sound like your mom was the one to choose this. Of course she isn't going to be sane about it, at least not calm like your dad.
And by the way I'm talking from personal experience, my dad divorced my mom when I was 2 or 3 years old. I'm pretty sure she didn't react as badly as your mom, but she definitely holds a grudge against my dad for doing that (although parents still get along just fine.) It's going to probably be harder for her without your dad, and also harder to find someone else at her age. Yet, you can't blame your dad because it sounds like it's hard to work with your mom, as my dad found with mine.