Lots of predators use the term BDSM as a segue into rape. Rape with someone who believes they need to be totally submissive to the
supposed dominant. It is easy to get a submissive person to get all confused about just this. 'Was it my fault I didn't stop it?' Well, by nature of the dynamic, no, you couldn't stop it. Not if you don't have a safe word and a contract.
It was not your fault however, if you don't want it to happen again it will be your responsibility to assess properly the worthiness of the person you say yes to. If you don't have an understanding of your rights, never say yes to BDSM.
The idea for you would have been to give consent, for a mutually agreed upon scene(s). Your partner created and acted upon a scene that did not give you the option to give prior and proper consent. Real dominants would have tied him up and whipped him in the village square if they knew what he did to you.
This is what consent looks like. It is imperative for safety. Always. Nobody touches you without explicit consent. No exceptions.
Dead Link Removed
This link is an actual form that 2 or more people engaging in BDSM play of any type should be interacting with, filling in, discussing, prior to any scenes or forms of play. Jay Wiseman is really well known and respected in the BDSM community. This should be filled in (by the submissive) prior to play. And dominants don't get to override the submissive when filling this out. If they try? Get the f*ck out. Immediately.
BDSM -- "Negotiation and Negotiation Forms" by Jay Wiseman
No Dom/Domme worth their salt would do to anyone what was done to you. Ignorance is no excuse. If someone claims they just wantt o try BDSM? Insist that they learn about it first. BDSM requires vast knowledge. How do you tell if a dominant is new or a fake or a predator? Easy.
They don't take time with consent.
If there is no consent (for whatever reason) run, don't walk, to the nearest exit (forever). Nobody is allowed to smash your head against the wall, slap you in the face, tie you up, put gag balls in your mouth..... nothing,,,,, unless they have proven to you that they actually give a shit about your safety. Anything else is assault at the least, or out and out rape or worse. And assault and rape are not what BDSM is about, unless explicitly consented to, and if so, then assault and rape are referred to as playing and scening.
Sorry, for reasons on my own, which are probably not the reasons that you think, I am very passionate about people being taken advantage of in this way.