Replying to Family falling apart

Well, for 17 years I thought I had the perfect, happy little family. We live in fairly nice house in the country with an amazing view, but I was just awoken by the sound of slamming doors and my mom throwing around the divorce word with my dad.

A couple weeks ago I was digging through a dresser looking for a photo album and I found several journals that belonged to my mom. It looked like diaries that her psychologist may have given her to write in every day. Most entries were within the last 2 years. Of course, I started reading through that shit and it wasn't pretty.

I learned that she has been struggling with depression and anxiety since 1996 (a few years after she married my dad). Throughout these journal entries, she often mentioned his arrogance, and his stubbornness. He didn't like to agree with her. She also wrote about divorice and how she just "can't handle it anymore". She even mentioned how my dad had been messing around with other women.

I recently posted a thread about my bad relationship with my dad. I realized that over time, I have often defended my mom when he accused her of stuff. I have kind of been on her side (rightfully so).

He goes out to eat and drink with his buddies late at night. and my mom keeps it pretty low-key. She doesn't like to go out much. So you can guess who may be getting into more trouble. I'm starting to think he's a pretty shitty person.

I just want some input from you guys. Im just lost. Looks like a divorce is likely. Maybe they have been holding off until my sister an I are out of the house?

Have you dealt with a divorice or major fights between parents?