OP, you did say that you two live together and have no place to go if she were to kick you out.  

1. What she did is wrong.  She gave dude her address.  

2. Don’t run up on her with accusations because it does look bad but it could be that she stupidly gave her address.  

3. You know your girl, if you think she will kick you out, tread softly.   

Think about your options and replay all the way she will react.   I usually will tell people to break up as your girl has hoe tendencies but I don’t want you to be homeless at the same time.   The only advice I can give you is that, this isn’t someone you should spend the rest of your life with but at the same time, save money and move out.  

Knowing the situation, I wouldn’t confront her.  I’d be planning to leave.