Am I wrong? (GF related problems)?

So just getting to the point, yesterday me and my gf had an argument because on her Tumblr page I sent her an anonymous message pretending to be someone one random, asking racy questions in which she responded as if she was really interested.( questions like if she wanted to have sex ;), wanted to be my girl..etc) I just did it to see if she would turn down the questions and say no because she has a bf already. After she responded and I stopped asking questions anonymously and I confronted her saying why would she do that. She gave me the excuse that it was someone anonymous and she didn't know who it is. I told her to tell me the questions "the anonymous person" asked and she lied about that too saying that he asked for her number, if she had a bf etc...I just laughed because I know exactly what I asked her yet she is making up other questions. I told her why is she lying about the questions and she said she was not and she is reading it right off the screen...again I laugh because I well know wtf I asked her anonymously. She then deleted her Tumblr saying its causing drama between us even though I pleaded with her to not do it. I did this because before yesterday she made a post about her "Tumblr Crush" with a heart next to some guy and saying "see.. :)". That hurt me so much and we made up after we talked and fixed that problem. Then I just did this to truly see and feel better if she would turn the flirting down, but went on right ahead for me to see. Was I wrong to do this? Why would she do it and then tell me she loves me so much etcc... I feel hurt.