My fingers slipped inside her pussy

With Alice's playful movements, getting a little out of control, I lost track of my hands until Alice's moan brought me back to reality. I looked down ans realized that somehow, while trying to hold her ass still, my first two fingers and slipped inside her snatch.

I couldn't believe it. I looked up at Alice, she was blushing hard and I must have been too. I'm frozen in time, too horrified to even move my hand. This was my sister after all.