I can't know if you were good or bad, only you can judge urself. By the way I would write her, telling how you feel and asking for explanations.
Supervisors often don't remember we are still learning and, above all, how difficult is to speak fluently a language which isn't your native one. Oh, I'd not be very polite, considering she hasn't been a good supervisor AT LEAST I would say: If I have to give up with science, only because you think I was bad, you have to give up teaching, cause you are a mess.