I went through something kind of similar. I'd always heard losing your virginity would probably be one of the least enjoyable times you've had but I didn't realize how much I would actually hate it. Same as you, it just kind of happened just several hours after I met her. She was sweet and great but I didn't know her at all and I hated every single second in her bed. I wished it would end as soon as possible. After years I still regret doing it, because at the time I just did it to say I did it, even at 19 I was just your immature average guy that wanted to brag to my friends that I did it. At least I learned I don't ever want to be with somebody I don't actually care about. Can't take that time back now.