Sham marriage relationship?

I am currently living in my boyfriend’s house with his little brother. I lived here for over 2 years and helped pay for mortgage as well. My boyfriend little brother finally has his first girlfriend. The girl is bisexual and an international student who is married to a gay guy and lives with him in the same apartment, according to her, it is just to have the green card to live here in the country. My boyfriend little brother wants to bring her home but since I live here with them I don’t feel comfortable to see her or even be around her because I find her whole situation very strange.. Does anyone else find this relationship strange? And do I have the right to say I don’t want her in the house even though I helped pay for mortgage and even if it is my boyfriend house?

Sham marriage relationship?
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