Told my mom

Caitlyne • Bonus mom to 2💜💙 Bio mom to 1 💜
So I'm 4 weeks and 6 days pregnant! I'm only 17, and my so and I were going to wait the 3 months to tell our parents... 
But my mom had a gut feeling and asked me... At first I lied and said I wasn't, but I couldn't deal with lying, so I told her... 
He doesn't want his mom to find out yet, which is fine, but he was worried my mom would tell his. 
I made my mom promise she wouldn't.
But he's pissed off at me for having told her. I wish he understood the importance of telling my mom. 
Any advice on how to handle things?