Your not a horrible person, well at least you dont seemone :hug:
If you said no then yes it is rape, you dont have to feel a sicko because your body responded to a 'stimulus' even if your mind didn't want it to, if you didn't want it to happen and you said no then it is rape, your body can react in many ways even if you dont want it to. If your body 'responded' in the way it did, it doesn't mean that deep down you wanted it to happen, you know that you didnt want it to happen even if your did body responded to what was happening