NEED ADVICE, my baby's fathers sister is jealous of my pregnancy

I'm a teenager, and she is just out of her teenage years. She gave up her child for adoption that she had almost two years ago. She lost the rights of it being an open adoption somehow. She is the attention seeking type and has always come up with manyyyy crazy stories and been caught in them. My dad was very angry and unsupportive about the pregnancy so now I live in my boyfriends house. His dad is accepting and is helping me. She is angry that he is helping me, and angry at me and her brother for being pregnant, though it was not on purpose. She is talking major trash and is causing a lot of drama because she is jealous that I'm going to keep my baby, how can I make her realize that putting her baby up for adoption was HER choice, and I'm able to make my own about MY baby?