Should I be upset or just let it go?

*disclaimer * it was in the past when he dated this girl, but when me and my boyfriend started talking I would ask him like if I was the first girl to give him head and was I his first. He told me yes in the beginning. Fast forward now on our anniversary date, he decided that out the random to blurt out that his ex girlfriend swallowed his nut first. I paused for a moment

like.... What possessed you to say that, but I never said it out loud or showed me real emotions on how I felt about it

. It was in the past, but now I question like what else has he lied about.

I'm I thinking to hard or should just let it go... Currently pregnant with our first and I'm really not trying to argue because I'm guessing the baby knows him and all I want to do is stay under him and cuddle ❤ that's the only thing that makes me happy.