People get like this around big life events. My relationship with a cousin of mine basically ended when we were both engaged during the same time, and she was so entirely jealous that I was also getting married as well that she pulled all kinds of stuff to try to ruin my wedding. When she and her bridesmaids (myself included) were picking out bridesmaids dresses for her wedding, she told me I am strictly forbidden to say a single word about my wedding because this is "her day." Then she purposely took everyone to the bridal store where I got my wedding dress, went and pulled my wedding dress off the rack, and started telling her friends how ugly it was, right in front of me, expecting me to not say a word because she told me I can't. The only reason I still talk to that b*tch at all is because she's family and I'm stuck with her.
Just try to not let people like this get you down. It's usually jealousy, whether she actually wants/was trying for a baby and is hurt that you got pregnant, or else she is just jealous of the attention you are getting. I know it's much easier said than done, but try to avoid any revenge moves and take the high road - once this is all in the past, you'll be glad you took the high road instead of stooping to her level.
