Huia the situation makes a lot of difference, and in your case I can understand it.
The fact that she apologised once suggests she knows she does it and tries to control it, but actually only notices it when it is bad.
Why do you assume that slights like this are personal? most of the time they are because the person is thoughtless, generally rude, or insensitive and it has got nothing to do with you. And if they do not like you, so what? Nobody likes everybody, so there are always bound to be people wo don't like you.
I am the same age as you and had similar experiences at boarding school at a young age, but it just made me more bolshie and rebellious. I think we just have very different personalities.
What one can say with confidence is that there are other people who feel like you, but also plenty, who like me, do not.
Next time she cuts you out in a meeting. Speak up. say, 'Excuse me , you cut me out before I had finished speaking. Please let me finish what i had to say.' I have done that in lots of meetings, it would never occur to me not to.