Why do I resent my friend so much?

She's pretty, kind, smart, has the perfect job and the perfect man. I respect the fact that she worked hard to get where she is. She just seems to succeed at everything . When I met her boyfriend, I was happy for her but kind of jealous because they truly are in love. I'm single and still in school. I guess I resent her for being so happy and positive. She's always trying to get me to share her positive outlook on life because of everything she overcame but everytime I talk to her, I can't help saying something to wipe that smile off her face. It makes me feel good. Last week, when she was happy because her sister had a baby, I told her it's fine as long as the kid doesn't have a disease or his parents die. I don't know why I said it, but I was kind of happy to see her upset. She called me toxic and said karma would take care of me. I told her good riddance. I really don't understand why I resent her so much. Does this make me a bad person?