Re: Not coping with the new sensei
I think this is a decision best left for you to decide. Don't talk it over with the other students, as you don't want their opinion to rub off on you or vice versa.
The question that matters is like the others said "Is it worth it?" You claim she isn't "that good" and you aren't happy there. No one is forcing you to stay there, so cut your loses and move on if you feel that bad.
Perhaps what you are taking as "pissy" is something else entirely. Not all sensei's have the same attitutude or method of teaching. Obviously you aren't used to this kind of treatment and if she is truly calling you stupid, then you shouldn't put up with it. If on the other hand you are construing her words to mean you are stupid, then it may be your interpretation of her words instead of her true meaning.
Stay. Go. Pick one. There are no right or wrong decisions. There are decisions and whatever you choose, be prepared to live with what follows.