Did I go too far?

My girlfriend and I play a game on tordol.com in which we just take the dares however ual or demeaning they are. It's normally just simple, easygoing fun but the last time we played she got a dare that told me to belt her bare *** 30 times as hard as I could. We have rules that every dare must be played out to the exact words. She almost started crying when she saw what the dare entailed but knew she must submit. She has the most sensitive *** and I have ed her for fun before and even a hand leaves marks on her. She bared her *** and I whipped it 30 times as hard as I could and when I looked down to see if she was okay, she was absolutely balling. I felt so bad and I saw her *** today and it was almost black. I feel so bad but she and I agreed its the rules of the game. Did I just go too far?