My little brother is having a baby with his partner

Yeah hi everyone this is my first time posting on here I really need to talk to someone. I’m 29 almost 30 and my younger brother is having a baby with his partner and I’m the older sibling, I still live at home with my mum and I don’t have a partner and I’ve always thought that I would be the one to bring a grandchild into the world for my parents first but my brother has already beaten me to it. I’m very upset about the situation and I know it should be a happy time that a baby is coming but it’s really affecting me. I don’t like my sister law she’s done some awful things to my brother and I can never forgive her for them. My brothers also to young to be having a child. I feel like this life is nothing but a competition between us and he’s always winning. He’s always been the golden child and I’ve always been the ‘reckless’ one or the ‘black sheep’ of the family. I have spoken to a counsellor and they said I am griefing the life that I wanted and I haven’t got. Is that true? Sometimes I’m angry about it other times I’m sad and I cry. I’m jealous about it all and this weekend I have my sister in laws baby shower and I’m dreading it. It will be the death of me because she will be the one who gets all the attention chances are I will just end up dissociating from it all so I don’t have to deal with it. I’m not sure if anyone else has experienced something like this or knows of anyone who has maybe been through something similar as well? If I could get some advice on how I could maybe learn to deal with this it would be greatly appreciated.