My dom scared me, is that normal?

Last night my *dom and I did a scene and I genuinely became afraid and had to use my safe word.

He had begun slapping me, something we hadn’t discussed previously, and did is very hard, my teeth hit themselves.

We had agreed to go rougher but it was unexpected, we had never done it before.

He felt horrible after.

Is it normal to happen?

*dom not son

***

I did get proper aftercare. As soon as he saw I was actually afraid and had had flinched when he went to touch my thigh he stopped and said “yellow?” Which means “slow down, change position, things like that” I said our stop safe word. He immediately pulled out and asked if I was okay, what did he do. He said he hadn’t meant to hit me that hard and got carried away.

He has slapped me before, but like my toys, not my face.

He’s normally very gentle with me and lives off my pleasure. The slapping more scared me then actually hurt me.