I struggled with him for about ten / fifteen seconds before he let me go.
Never have sex with him again. EVER.
This is a dangerous, crucial time for you in which your boundaries are tested. What you are willing to accept or not accept is tested. What you decide now might decide the course of your relationship or more than that.
Only you can define what happened to you, but in my opinion you were very clearly sexually assaulted. It will take some time to get your head wrapped around that. First you will be sad and confused or both, and as time goes by and you realise fully what he did, you will get very angry. You are still processing it, and it took you by shock so your reaction does not surprise me. Never blame or question yourself for that.
You might be confused as to why this man, who has a name and a family, hobbies, maybe pets, a man whom you have fond memories with could do this. You might wrestle with that idea and try reconcile the two. Put it aside. What's important for you and your safety, is for you to realise that your partner gets off on sexual assault and torture. I don't care if you have consented to degrading acts in the past or not. This is a wake-up call as to what gets him off, and I wouldn't be surprise of there's more in store for you.
If you question or doubt yourself, here's a very good way for you to evaluate the shittyness of what someone has done to you - do you feel you can tell anyone this in real life? Does it seem so bad, that you feel it's shameful, dirty, something so bad that the person in front of you might want you to call the police? Is it so bad that it's illegal? That if you told a therapist or councillor they'd be duty bound to let the authorities know so they could support you? That your friends and family would be worried abput you? If so, that's how you know.
You have cause to take this to the police. No one can guess what's in someone else's mind, but this man does not love you. No matter what he says, does or pleads. No one does that to someone they love, and even if they did, you have no obligation to forgive them or stick around to see what they have next in store for you.