<human>: I debated posting for help about this but I really don't know what to do here. I have a cousin we will call him Rob; Rob was always the socially awkward one in our family. I felt that as his older cousin it was my responsibility to help him out. So I always maintained our relationship; we live far from each other but have each other added on social media accounts. 

Recently he added me on snapchat; and he ended up having a story of him with his girlfriend. And I stopped for a second because this girl looked EXTREMELY familiar. I later called him up and asked him her name, and yup sure enough it was a girl that my buddies used to sleep with.  

Back in my old house, my roommates used to always throw parties, and there was this girl that used to always come around. And she would always spend the night. And they would videotape her sucking them off, they would have threesomes with her while one guy recorded. Even I have gotten head from this girl… 

Now, she is dating my cousin. When I asked him about her, he thought of her as an angel, said she has only slept with one guy before him. Furthermore, he is thinking about marrying her and all. Now, the thing is I am worried about this, he is in medical school right now, and honestly I am worried that this girl is lying to him to use him for his money/potential earnings. He has even told me that he bought her a bunch of extravagant gifts. 

As my bro, I would just tell him but I feel though that since this is likely the first girl that he has been with, he is going to look at me as the bad guy and his girlfriend will pin me as being jealous etc. I was thinking of collecting evidence from my old roommates (videos/photos) and then showing them to him but I don't know if that is the best idea either. What do you all suggest? (I am posting now will reply after I come back from gym).

Can you condense the text into three sentences or less?
<bot>: socially awkward cousin got his first girlfriend. I am worried that since he has been forever alone for so long that he is being manipulated by this girl who is only using him for his money.