Has anyone else come to a point in their life where they feel like they can no longer understand the person(s) that raised them?

I've Been struggling with it a lot lately. I really only have had one parent. My dad (although he lives with us) has been a perpetual 5 year old and never filled a parental role. Never has he been there for us. The only time he has ever gotten "involved" so to say is to sabotage the family with emotional abuse and his revenge for abuse that occurred when he was a child. With few friends, my only go to has been my mom really (though i have finally made a close friend who i can talk to). I have always had my own opinions but i didnt say much because i either was shut down or too scared to tell her because she would get so angry or was too busy dealing with my dad. I'm moving out soon and the more and more i think. The more i realize i am angry (not just my dad) at her for not getting a divorce and events that have happened. I feel like i can't tell her because i she A. Wont get it B. Tell me i am wrong for my opinions and C. I dont want to destroy the one relationship i have. I act like i am okay, But the stress just kills me and i gotta do whats right for me. Our family as an entirety has never communicated well and i just feel so lost and betrayed. I use to think i could tell my mom everything, but its not true. I go through lots of things in my mind, and i feel like i can't tell her. I get really depressed and have thoughts about death. She doesnt even know or she doesnt acknowledge it (ive tried to tell her before but i get shut down pretty quick usually because she tries to rationalize why i feel a certain way instead of listening). She always tells me to smile, why smile if i am not happy? Its Like we are on two frequencies is the best way to describe it and the divide grows greater as time passes. I feel like she doesnt see how badly her actions affect me....

Even with that, i feel that i NEED to tell her because then i can't say i didnt try and i'm going to be gone soon (moving out). I need to get the weight off my back. I have a really hard time talking about it so i wrote a letter. Its now been a week and i still haven't given it to her i guess for fear of retribution. I've written notes in the past and gotten yelled at for doing so.
Has anyone written a note? or can relate to this?