I don't think you need to create a forum for this problem. You
can get consultation in Aunt Agony forum.
Anyway, I think you should try calling the unknown number in his
phone.
From your paragraph, I understood you just had your first baby, so
I think "he" would devote more time for you and your baby.
Married couples should be honest with each other. So I think "he"
should come clean with what he did.