Nairalanders.....

I know some of us have been through things like this. Please advice me.

What do you do when something is really bothering you and it's not something you want to share with your girl cos it's about family. Unfortunately she happened to be in your house when you got back from your family house with this long face. Since then she won't stop asking you what the problem is. Because I don't want to lie to her, I keep telling her am fine but deep down I know am not.
She finally tells you "you know we tell each other anything, but then if you don't tell me this night, I won't ask again in the morning"

Somehow as a man way I be, I just want to deal with the issues first within myself before I talk to her but she just won't understand. She's just saying so many things and asking too many questions;

1. Did I offend you?
2. Do you want to break up
3. What is happening to us? Etc

Her questions are even compounding my thoughts. What do I do? Should I just tell her what's up or lie to her?