No, no, he has not been violent against women in the past. And in the dojo nor "really" violent against men. He has been reported to the police (and got punished by the court) for other things (betrayal), not for violence. It's more a strange, hard to describe "aura" around him, that can be very scary. Usually he is very nice, very charming, friendly, a good person, nice to talk to, nice to be with him, wonderful to train with. But he has also a dark side, that you sometimes (very seldom) can see for a short time. He has a lot of temperament, is very large, of enormous strength and a very well trained martial artist. There are other men of his size/strength at the dojo, but they don't have this "odour" of potential danger. I could describe it better in my own language. It's as if there were something in him, that is so very strange, not really evil, but strange, that no one can have contact with this part, not even he himself. But these are only feelings. Maybe they are wrong and very unfair against him.
Dear Anonymous - Earlier you wrote "He did abuse me sexually (oral) ..." If you are under the age of consent, or were not a completely willing participant, then it's rape. Maybe in your country it does not meet the legal definition of rape but that's what it's called.
Your sensei appears unwilling to support you in dealing with someone that's raped you, has this "odour" of potential danger, and also from what you have described, is a predator.
Trust is a very important part of training and the foundation of trust comes from your own feelings. If you were to meet someone and had the "feeling" that something is wrong then trust yourself. Right now it seems there are at least two people in the dojo, your sensei, and B, that you can not trust to keep you safe.
You need to leave - save your money, keep in contact with people at the dojo you care about, let them know what happened so they can look out for any women that join the dojo, and some day you can train again. Ideally, "B" gets kicked out of the dojo and you can resume training there.