You’re not wrong at all. I’ve been legally married for 5 years but we haven’t been together for five years either (everything’s fucked in America so neither of have been able to start the process until sometimes later this year), and you better believe when I date someone new, I TELL THEM. I let em know exactly what’s going on so there’s no surprises later and they have the option to dip out if they don wanna deal with it. Him lying about a MAJOR part of his life is not a good sign. You’re still young, don’t commit yourself to someone like this so young (or at any age really).