How to hide gender disappointment?

I found out 2 weeks ago that I’m having my 3rd boy. Blood test confirmed today that it is in fact a boy. I have been struggling to accept it. We really thought it was a girl this time. Today my sister in law is having her gender reveal party for her 3rd child. Is it wrong to be nervous? She has 2 girls & is really hoping for a boy. I hope she gets her boy & I don’t want to feel jealous but I’m afraid I will break down. I’m already emotional that it has been confirmed by ultrasound & a blood test that I’m having a boy & debating on if I should even go because I want to be supportive & be excited for her but they get their boy then I might cry😞 I just wish mine wasn’t confirmed today so I could hide my feelings & be excited for her but I’m super emotional right now.