Cousin drama should I leave it alone?

So I have a cousin who at one time in our life we were very close. When I became a Christian we started to separate we no longer hung out as much as we did, when we talked it was sometimes awkward but we tried. So in march of 2009 we both took a trip to San Francisco we had a good time it was like old times we were just reflecting on the past and the stupid mistakes we did. All of a sudden she drops the news that she is expecting a baby with her looser boyfriend. Of course I was excited for her, but than reality hit I asked her how she was going to support the baby with her only working and her boyfriend just munching off her! I swear I could not stand him but anyways so she told me not to tell anyone, I said I wouldn't. So a week later I was talking to my mom who I am very close with and I spilled the beans I told her. So days later I get a text message from her and saying how dare me tell my mom how could I blah blah, I apologize and said there is nothing I can do anymore. Well I went over there and went to talk to my cousin and try to work out our differences but she told me I was as good as dead she wanted nothing to do with me blah blah I was crushed, i know I made the mistake of telling my mother! but give me a break! She is the type of person who holds grudges and can not get over things. till this day she still dose not want to talk to me! Am I really a bad person I know we make mistakes but I miss my cousin and I no I need to pay a price but come on this long? I made the effort but I get upset because she is taking this way too far my family agrees as well. should I just leave it alone?