A Slam WHAT?

On Saturday I was sitting down eating a late dinner with my oldest daughter (10) just the two of us. My other daughter (6) doesn't eat food only if it's a Pop Tart and my wife was off in the other room screaming and yelling about something I did or didn't do, I still have no idea what the problem was. So when my wife gets mad she cleans and I don't mean she dusts, she goes in our rooms and starts to throw stuff out with out even asking if you want it or not. So trying not to pay any attention to my wife my daughter and I were talking don't remember and you'll so see why. Now before I go on you must know that we talk very highly about the oldest on how she's always kind to others and things of that nature and we didn't do that just because she's our kid she really is or I should say was.
Okay here we go I was almost done eating when I hear my wife coming down the stairs. Now I don't want to look at her so she won't yell at me, then I hear a slam on the table when I look over I see what is my oldest daughter's journal then I look up at my wife to see tears in her eyes and see tells me you better read that and then looks at my daughter and said I thought we raised you better than this. Now any one who is the father to girls knows we don't want to read that book. Because I got sick just thinking of what I was going to read. As I pick up the book my daughter begins to cry an I think to myself holyshit what the hell is in here. I remembered the other day she had that book in her bookbag for school and when I went to pick it up she freeked out saying don't it's my journal leave it alone and pulling it from my hands.
So I open the book and my wife says turn the page and when I did I could not believe what I read. It turns out my daughter was writing horrible things about her classmates, words that I never thought I would ever hear let alone read. This one's a Bi@th and MotherFu@king this one and this one probably would have sex with the principal and have 1000 babies and this one's mother is this and that and so on and so forth. I was relieved in away that only a father could be, but then I was so angry that she would do something like this. So I found myself yelling "What gives you the right to write these things about other people?" She said that they were mean kids I told her that she was no better for what she was doing. My wife told her that she knew that it was called a Slam Book, A Slam What I screamed the only thing that should be getting slammed is your ass with my hand. It turns out that she was not the only one writing stuff in that book, she had two other girls writing as well which I do believe because you can see the different handwritings. I don't know how I controlled myself but she did not get smacked at all. She did get a list of punishments that will be in place for a long time. We also decided that we would not say anything to the other kid's parents but might say something to the teacher so he knows whats going on in the class. So what would you do?