I just want to cry.

My sister-in-law who is a terrible person just had her 3rd child today and I just want to cry. I have been ttc  baby #2 for a few months now and I'm just frustrated. My son is constantly asking when he can have a brother or sister and I want so badly to give that to him. I'm happy her baby is fine and she's okay I'm just having a moment of selfish jealousy. Can anyone out there relate?