To know the sex or not to know that is the question!

Levaun • Taking this trip down baby lane yet again. While this is our third pregnancy together , this is our first🍼
So my first child I knew the sex and I kind of want it to be a surprise for me. 
I want my S/O to know cause we both agree he should, but I know I will be able to tell by his face... He says he will be excited no matter what but I know the difference between I'm excited and I'm over joyed... So the question is do I just find out or do I just let him know instead???