My boyfriend ruined everything.

So I'm pregnant with NY second child, my boyfriend currently has a daughter who's 4 and I have a daughter who's 5 were expecting our first son together July 24th. Anyways, we both agreed before we went to our gender reveal appt this past Thursday that we wouldn't tell anybody until we either did photos together with both of our kids or until we did a gender reveal party, we didn't even know the sex or have the sonogram photos for 2 mins and he was already texting his mom telling her the sex. I'm completely upset and ever since I haven't even been excited over anything anymore. I know this isn't my baby's fault and I shouldn't hold a grudge but we both agreed not to tell anyone. 😠😧😭