I still don't know what happened...

So, yesterday, I wanted Ceci to clean her room.  It was not too bad, but I didn't want it to get out of control because then she gets overwhelmed and melts.  Well, she just wasn't having it.  So, I did the old "I'm coming in with a trash bag" routine.  Not the first time.
Oh. Dear. Lord.
She went nuts.  She was howling and standing in the hallway, clutching the doorknob of the closed door.  I said, "Let go of the door, or I will get two bags.  (They were Publix bags.)  She does not budge.  I go get another bag.  She does not move.  I physically remove her from the door and walk in.  She shuts the door and resumes clutching the doorknob from the outside.  I am not exactly sure of her logic at this point.  Maybe she was thinking I would not be able to get out of the room; therefore, I could not throw away the bag.  I don't really know, but I tried to open the door to explain to her that if she came in and picked up a few things before I could get to them, that would save them from the Goodwill bag. Instead what happened is I forced the door open, started to speak, and she came in, and I say this quite literally and not at all as a cliche, but she came in as I imagine a bat would exit Hell.  Arms (wings) flailing, silently, desperately grasping for the Publix bag in my lap which contained a dollar store Tinkerbell puzzle and two Mc Donalds toys.  (Do you really think I am going to put the wooden dollhouse furniture in the Goodwill bag?  That Plan Toys stuff is NOT cheap!) She's freaking out, so I lift her up and place her in her bed.  I turn to resume my quest for crappy toys, and she SLAPS ME on the back.
Oh no she didn't!
I turn slowly (in all honesty, stifling a laugh because the intensity of the situation is such that I don't know WHAT to do) and say, "You do not ever slap Mommy.  I want you to spend the next hour in your bed.  I am going to take out every stuffed animal. (All 45 of them) I am not going to put them in the Goodwill bag.  They will be put away.  You will have nothing in your bed."  As I am saying this, she attempts to throw an empty plastic bag at me, which is both terrifying and ridiculous, to be quite honest. I deftly remove all pencils and markers from the bed lest she attempt a stabbing.  I get a good clear look in her eyes at this point.  She has crazy eyes. This is the first time in my parenting career (and I am sure not the last) that I really, truly do not know how to handle the situation.  Not even in inkling.   It is so intense that I laugh and say, "Ceci, you have got to calm down." This seems to cut the tension, and she goes from frantic caged animal to crying girl.  After she calms down, we have a talk.  She spends some time in her bed, alternately wailing and playing, and when the timer buzzes, she happily comes outside to play with the boys and I.
Geez. Lou. ise.
But even after that, I still think she's easier than the boys.  For now.