Baby shower for my sister in law

Hey ladies. Need some advice. My husband and I have been TTC 19 months. It’s exhausting, grueling, a total nightmare. My sister in law is pregnant and due in December. She was very hesitant to tell us as she knows what we are going through. Now my mother in law is planning her baby shower and can’t stop talking about how excited she is.

I guess what I’m asking is how do you deal with these feelings? I obviously am happy for my sister in law but talking anything baby brings my entire mood down. How can I put on a happy face for her and my mother in law? I’m not really sure how to deal.