forgive my mom

I really just want to get this out, maybe to help myself work on the forgiving or just to have someone who may actually understand how I feel.
When I was six years old, I walked in on my mother cheatig on my dad with a man she worked with. I had no idea what was going on, and honestly I still don’t want to think about it, but that is the day I knew it would never be the same. My father found out soon after and the fighting began, it was a scary time in my life. My father who is not usually a violent man, raised his hand to her but thankfully he hit the wall instead but in that instant I knew there was more. My brother and I were sitting on the stairs watching the whole thing. We cried and I swore I would hate her for doing this to us.
That wasnt the worse though, the next day when we woke up she dropped us off at school and said goodbye. And she disappeared for three years. We never heard from her. She came back shortly when her mother passed away, stayed for two weeks then left again.
This is what I cant forgive her for. She has missed, 12 birthdays and christmas’, my high school graduation, senior prom. But the thing that has really bothered me most is that I missed having a mother to talk to when I needed to. And even today, we talk once a month for 5 minutes and I still am not over it, and I cannot bring myself to forgive her… not yet anyways.