I also wanted that and asked my husband to keep it a secret he semi did it. he told all his battle buddies and i get it he's happy i let it sly i mean like the other girl said better him happy then not. all that i care is that he hasn't told family i want to wait till in out of my first trimester to be safe. And i know that my hubby can't keep a secret so im happy that at least he's doing that much for me. try to cut him some slack.
My bf was the same but I know it was only because he was so excited. Tell him you didnt want him saying anything and in future try to respect your wishes.
Talk to your bf. Maybe it slipped out. Maybe he's so excited he just couldnt keep it in. Explain why you feel the way you do, about being alone.