My girlfriend came to my house last night scared. She won't tell me what happened and it's worrying me.?

My parents let her spend the night with me because I think it has something to do with her brother, whom she has never talked to in her life, showing up at her house unexpectedly. She's in my room laying down, and I called her parents and they said that they have been having issues around the house and that I should hear whatever happened from Lexi, and not them. I know her dad means well, but sometimes he can get a little insensitive. I don't think that this situation is a violent, I just know that at 10:00 pm, Lexi knocks on the door, my parents answer, because I'm in the shower, I come out because I forget a bar of soap, and she's crouched up in the corner on the floor, crying. Something's seriously wrong and I have got to find out what it is. I don't want to pry, but I have to know and I think she's scared to tell me. What do I do? We're 16, If that helps at all.