My boyfriend has a child

So I’ve been dating this guy for a short amount of time, I’ve known him for a couple months but we finally made it official that we’re together. Today I had a pregnancy scare. He was there for me, but he revealed that he has a child. She’s 7 months old. He then reveals that he’s paying his baby mothers phone bill. I’m mad, not at the fact that he has a child but because he lied about it. I jokingly asked him if he had kids when we went out the first time and he told me no. I’m trying to go about this without cussing him out but imma go crazy. I wanna smack tf outta him 🤦🏾‍♀️