I pretty much felt the same way you did after my first same-sex encounter, which was just mutual J/O with my college roomate and he gave me a little oral. I was not attracted to him and the encounter overall wasn't that great. It's pretty sad, but I was very freaked out about it, hardly slept that night, and I was so rattled by it the next day, I couldn't concentrate and went in and totally bombed the final exam I had to take and did some serious damage to my GPA. I wish I hadn't reacted so negatively to it. I felt very alone and confused, because I was definitely very attracted to women and definitely somewhat attracted to men. This just threw me, caught me off guard, and I did not know how to process it.
Today, I am completely accepting that while I self identify as about 3/4 straight, I consider myself about 1/4 gay. It's complicated, because I'm married and find myself mostly attracted to women. But, there's no denying that I feel definite attraction to men - and I don't feel bad about it any way. I'm guessing you're younger than I am. So, my advice to you, and I wish I had done it myself, is be open to your same sex attraction. You know you wanted to do it - don't trivialize it by chalking it up to just being horny. Don't worry about labels (I still don't know of any that completely apply to me), and feel good about what just happened. Be open-minded and positive.
Good luck to you!