What should I do?

My boyfriends ex girlfriend is pregnant and ive agreed to work woth him on keeping the child in his life. But now shes targeting me and saying my miscarriage i had a few months back was a lie. But its not. This shouldnt hurt me knowing shes making things up. But it does because I was the one that lost a child. She has no right to say those things to me about my child i lost. What should i do? Emotionally it hurts. I know i shouldnt ger mad at her. But that is such a horrible thing to say. As well as a sore spot to hit me.