Boyfriend LIED about being american

So me and my bf have been living together for a year, we basically moved in together right after we met. He told me he was born in america and he married a girl just so she could get citizenship to the u.s. Then divorced once she did. This was like 8 years ago. But I just went through some of his papers and turns out that HE actually wasn't born in the u.s. And it looks like she married him so he could get HIS citizenship. It's been a year of being with the guy why the hell does he think he has to lie to me? He should know that I wouldn't judge that he is an immigrant. I feel like I can't trust him at all now. I also found the marriage papers but I can't find any divorce papers. But I looked her up on fb and she has nothing on there about ever being married so I do believe they are divorced but I don't fucking know now. I feel so betrayed, the guy I see a future with lied about the place he was born and basically a good chunk of his life and doesn't care that I know the truth. That means every time I've asked him questions like "what hospital were you born in?" He lied to me every time. What would you do?