Was reporting my ex to the IRS wrong?

I recently found out that my ex cheated on me in the past and I had already forgiven her ONCE before that for finding out online cyber affairs. She never met these online people but eventually she met someone at church (without my knowledge) and she SAYS they ended up going out only ONCE and he kissed her ONCE. She swears that's all that happened but I don't have much reason to believe her. Anyway, I was so angry and in a state of temporary insanity I reported her to the IRS for unreported income (she rents two rooms in her house and never claims it). In a weird way it was my way of getting her to LITERALLY pay for her betrayal. It doesn't make me a better person but I'm human and nothing hurts more than being cheated on. Specially when I had given her a second chance at love since originally it was just an online thing. I have mixed feelings about reporting her to the IRS. On one side I feel it was like a "payback" or the perfect revenge....On another side, I feel I could have been better than that. But hey, I'm not the Dalai Lama.......At the time, I just wanted revenge and I can't say I regret it 100% either. How would you have handled this situation? She wanted to remain friends because she said I was the most important person in her life and that she still loved me and really feels bad for everything she has done. I almost feel like I had to break her trust as well just to get her out of my life all together. For MY sanity. I wanted to reach the point of no return where all trust was broken so we couldn't even remain friends.