Hi MeghanLynn,
I'm so sorry you are having to deal with such a shaming, blaming and childish parent that is your mother. It is abuse alright, no doubt about it at all. Your mother is wrong, very wrong to be saying those things. It sounds like you and your poor sister can't do anything right.
I am afraid to say that her words and actions can leave some long term damage for you and your sister. NOthing you may not be able to overcome but she could leave you with attachment issues that have the potential to stop you guys from attaining healthy adult relationships.
Your father has no right to 'checkout' of the situation and turn the other cheek like he does. Can you ask for him to be more responsible and see if he can adjust his shifts, or at the very least have you and your sister stay for more time? I"d really like to see you guys spending more healthy time together, away from your vindictive mother.
I also would be harbouring fears for your sister (younger, I assume) with you away in college your mother's abuse may even escalate even more, and if she has no-one to turn to she could suffer greatly.
You and your sister's self-esteem is under constant barrage from your mother. I strongly suggest you get some self-help motivation books for teens from the library and/or seek some counselling either face to face or from a phone service at the minimum for you and your sister.
Although my mother wasn't as bad as what you are speaking of, they definately came from the same pod. I can remember my mother going on and on and on and on and on and on, and just droning on and on some more, mostly centred around my hateful and destructive ways and she'd be highly critical of almost everything I said or did when I hit my teenage years. Our whole family became fractured with me leaving home early at 19 married and my 2 younger brothers rebelling and getting into all sorts of troubles. At the age of early 30's I had to seek counselling to deal with tonnes of issues regarding my parenting, especially my mother. I'm 45 now, and only just realising the impact she has had on me and why I am the way I am in some things. I always thought it was 'me', it still is me, but now I'm seeing it's a result of her highly critical comments and constant put-downs.
I still see my Mum regularly enough after a long 15 year break away overseas and interstate because I have 'forgiven' her in my heart, and today I can tell her 'pull her head in' when she starts on down her usual track, but she's on medication now which has calmed her down immensely, plus she's running out of puff in her mid 70's.
Anyway, I hope this has helped. I'm always concerned for kids when I can hear the words of my mother and her actions being repeated as I know the consequence of having to deal with low self-esteem issues, under confidence and fear in trying to make a successful life for yourself after abuse, it's not impossible though.
I wish you and your sister the best, but really, if you can get your sister out at the same time you go I'm thinking she'll love you for it in years to come.
Take care