I had sex with someone the other day.
For context, I (18M) have been in a very stable, and a very healthy relationship with my fiancée (18F) for the past year. I would also like to note that what I'm writing is the truth and it posting it anonymously, here, was the only way I could get some sort of help.
In short, I've been a fairly heavy drinker, even since I was younger and Saturday was no different. My friend's brother was turning 18 and I had an invitation since I was a family friend.
I ended up going to the party and met a few people, had some fun, had some alcohol. Maybe a little too much, causing me to blackout. I don't remember much of the night other that drinking and laughing.
I ended up waking up in the guest room with no memory of the night before and realised that I had no clothes on. I panicked a little bit but since I had just woken up I didn't fully process it.
I turned around and saw this blonde girl already awake, she looked at me with a smile in her face and said 'good morning handsome'. I lost my voice and started to have a panic attack. I have no idea who this girl is and no idea how we both ended up naked in the same bed. I didn't know what to say and I just asked 'who the fuck are you?'. She didn't answer my question directly at first until I asked again. Even that answer wasn't good.
Not long after she answered, she pinned me down to the bed and went down on me. I really tried to push her off but I had just woken up and I had no strength. She spat on it and stroked it whilst blackmailing me. Showing me that the night prior had been recorded. She took advantage of me and is now threatening to ruin my entire relationship. I covered my eyes and cried a little bit.i regret moving my hands though because she mounted me and started to ride me. She didn't stop even though I cursed and tried to forcibly get her off me.
I ended up climaxing inside of her and now she's saying that if I don't hook up every once in a while. She'll show everyone the video. I refuse to do it again. I didn't even consent to what happened and I was too hungover to prevent it. I don't want to lose the love of my life to blackmail.
I want to know if I'm in the wrong, what's the best course of action? How can I talk to my fiancée so that's he understands?