sounds like a difficult situation, especially because you live in the same place so you're likely to see each other pretty often. do you have the same group of friends? in that case it would be even more difficult i guess...
well sounds like her boyfriend kinda knows that you're very close friends even if she didnt tell him.
losing friends is painful indeed. i met my boyfriend some of my most amazing friends when i lived in england. it was so damn hard when i had to return to my country and it still is. i do keep in touch with them but some of my friends there dont have internet at home, which doesnt make it easier.