Does anyone else think it's selfish or am I being jealous?

My sister in law recently just had a baby a few months ago and her and her husband are planning another one already. Call me cold hearted but her marriage is shambles. Her husband is violent towards her and pushes her down the stairs and on NYD they were both drunk in the house with the children arguing in front of them and they have announced they are planning on having a baby. Her husband has given her STDs and cheated on her and she has also cheated on him. Me and my husband fell pregnant in January and sadly I lost our baby. Every time he mentions his sister or she speaks about it I just get very angry. She really pisses me off and I fell like telling her to close her legs and look after the children she already has. It breaks my heart because people in marriages like that are blessed with the one thing that we have ever wanted and we have to go thru that. Life is so unfair.