Why do I resent my friend so much?

She's pretty, kind, smart, has the perfect job and the perfect man. She didn't get everything handed to her and she worked hard to get where she is. She just seems to succeed at everything she does and her life is like an A&E special. 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. I can't help it. 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?