His ex-wife

So my boyfriend and I have been together for a little over a year and a half. Everything is perfect between us except for one thing. He was married before. He's 4 years older than I am and he was married while active in the army. Their marriage didn't last long. From my research it last 2 1/2 years. They meet a couple months before he left to basic training and they got married a month or so after he finished basic and they moved to a different state to where he got stationed. Long story short, I did some research on her social media and found a lot of info and now every time he talks about the army I remember things I found on her page. What state they were in when he proposed. How he proposed. A stupid lamp that was in their room. The dresser and night stand that was in their room. Christmas decorations. I've seen too much. He doesn't know of course. Sometimes his family talks about his past. Mostly asking him questions about their dog. And one time his cousin said her name and I became furious.

I hate that he was married before. I can't get over it.

Recently he received a phone call telling him he'll have to go to a different base anywhere from 6 month to a year. He asked me if I were willing to marry him so we can move together. My mood immediately changed when he asked me and he knew I was upset. My theory is that he married to get more money from the Military. I do want to marry him but not so I can travel with him or so he can get more money for having a spouse. To top it off, she still has his last name.

I've thought many many times of leaving him for this reason. It sounds silly but I just can't get over it. He know I hate this. And I know my attitude towards it gets him upset. I honestly cannot control it. We have talked about this only a few times. I don't know what to do.