Why is she mad when she is at fault?

today my wife found out that i had a key logger installed on "MY" computer. The reason I put it on the computer was after she opened up a facebook page I saw where she had been searching for a man that she met about 7 years ago and would keep in contact with him behind my back. I saw where she told him that she loved him and was empty inside because she wasn't with him and how she wished she had made different decisions back then. Even though we kinda worked things out I still don't trust her as far as the other man in concerned so I left the key logger on my computer. now she is mad and is acting like she is a victim and I did something wrong. when all this came out she was more then willing to do what it took to keep us together so why is she mad now its only been 6 months since all that happened i found out about it right after thanksgiving so it totally ruined the rest of the holidays for me and even then she never really wanted to talk about anything she just wanted it swept under the rug and forgotten about. she has her own computer that I don't even bother so if she is still talking to the other man or anyone else I wouldn't ever know it I only know what she did on my computer. So what do i tell her besides I feel like I needed at least this much to have some kind of reassurance that she isn't doing anything at least on my computer anyway.