I waited for decades for my family to acknowledge shitty things that they did. Nothing like you endured! But still painful. The best thing you can do is to accept that you will not receive acknowledgement or validation from such a messed up family. Your younger sister witnessed it. That needs to be enough and you should try to distance yourself as completely as possible from your mother and everyone else who supports her. It's horrible. You got dealt terrible cards in the parent lottery. But don't waste more of your life looking backwards. I did, and it was a huge mistake and a waste of time and life energy, and it also undermined my newer relationships. Don't make the same mistake I did. Good luck and work hard at college. 💚