There's a whole heap of misunderstanding here about what BDSM is. It is not, by any stretch of the imagination, "Anything goes".
Rape is sex without consent, and that can occur at any point - a person can, in their mind, stop consenting at any point. It's pretty clear to me that what you're saying ia, "I didn't agree to that...". And that makes it rape.
Whether or not he'd be found guilty of that in a court of law is an entirely different question.
He's asked you whether you consent to BDSM. But this wasn't BDSM. At all. and it's not a free pass to him that you agreed to BDSM, because you still have to know what it is that you're actually agreeing to. And clearly, you had no idea.
If you consent to a doctor taking out your tonsils, and they remove one of your kidneys, did you consent to that? No. Clearly no. If you had no idea what removing your tonsils would actually include, does that mean you consented to your kidney being taken? Still no.
BDSM or not, at any point (ANY point) during a sexual encounter, when you're no longer consenting to what's being done to your body- that's rape. His criminal culpability doesn't change that.
The fact that you were too frightened to tell him to stop? Is very (very) common with rape.
I'm sorry this happened to you. There's nothing about what you've described that is BDSM. What this guy did to you? Is abuse.
Be gentle with yourself. Do you have a T? Do you have anyone supporting you?