Guilty Secret

I told my partner I had a kink for CNC roleplay and wanted to act out being kidnapped. She agreed but said she didn't want to talk about it afterward. We started, everything was consensual and clear before we began. But during the scene, when she pretended to be scared, something in me snapped, I forced her into submission with my words and actions, pushing past our agreed limits without hesitation. Is this normal? Am I a monster?