Feeling disgusted and scared after sex

I was at a dance party and I met someone there. She invited me back to her place to drink and when I was drunk we ended up doing stuff. It was fun while we were doing it but as soon as we finished I suddenly sobered up and felt horrified and disgusted with myself. I felt scared of her too, I didn't want to be near her or touch her and her scent made me want to throw up. I ended up sitting on the bed shivering for hours and was unable to sleep. I felt like I was raped almost, but I enjoyed it at the time. Why did my mentality change so fast? Now I can't even think about it without wanting to throw up and hide under the blankets.