Am I going insane?

I need help! I just hit my dog. I don’t know what happened. He just nipped me and I hit him so hard. I hate myself so much. I would never ever do that! And yet I did. It was like I wasn’t even doing it. I felt like I had no control over my body. I have cptsd and I think it is making me go insane. I am so ashamed. Please don’t be too rude to me. Does anyone know what could have happened? Am I just an aweful person?