Why did this womens comments bother me so much?

I work for a landscaping/construction company, and last week end, one of my co-workers asked me if I would help him with a side job, for a women that didn't have the money to clean the moss off of her roof. He told me that she is a really nice person and she works with the homeless, so I said sure. I do alot of bad things, so I need to do good things to make up for them. So, while I was on her roof, working for almost nothing, I over heard talking to my partner about me. She told him that I looked like a total creep, and she told him to not leave her alone with me. Now, I didn't even say 1 word to her the whole time, I just smiled and kept my head down and focused on what I was doing, So when I heard that, it took everything in me to not spit in her face. I also came to find out, that the reason my partner was helping her, was because he is screwing her (She is married). He told me don't worry about it, but I am sorry, that isn't good enough. So... In the middle of the night, i went to her house, and I threw a brick through her window, and on it, I wrote "your wife is a whore that F**ks other men", and for good messure I also keyed her car really good. But it still bothers me what she said, I want to hurt her..... Not in a phyiscal way, but I want to make her suffer.... I have always been this way, I just don't like it when people get away with treating me unfairly. Let other people be the better person in a bad situation, because I am the type of person that will always throw gas on a fire, and see who gets burned worse. I think tommarow I'll go back and set their trash cans on fire. Anyway... Why does this bother me so much, why can I just brush off what some stupid b**ch says?