Should I marry him?

Good morning, everyone! So I’ve been dating my partner for almost 5yrs now. We’ve been talking about marriage for the last year and I was willing and ready to marry him until last year. We got in a heated argument that led to him telling me he had a vasectomy years ago. Now, prior to this argument he NEVER told me anything about it. 5yrs with him knowing I wanted at least 1 child and he NEVER told me. Granted, he has 3 kids already and I have none. He constantly told me it was reversible during the argument, but I’m not sure if we should still get married. That secret was a HUGE one to keep and with him knowing I want to be a mother, I just can’t wrap my head around why he wouldn’t tell me. Now, I’m stuck because I don’t know if I should move forward with the marriage or not.