It's not your fault!! This is all one big learning experience for all of us. Anyway, Peanut used to have TERRIBLE PMS when she was in heat. She is normally a very sweet and mellow girl, loves everyone, never barks. I remember she would just get this evil look on her face and sit on the couch all day facing away from everyone.
I remember my vet had me wait two months to spay her... not sure what the reason is though. Don't worry, her mood swings are temporary.