My girlfriend told me she has oral contraceptives, what should i do?Please help

Actually, this girl was my ex-girlfriend, we broke up 3 years ago but a few months earlier she came to Beijing and met me.
We fall in love again, i still remember that night, she lies in my arms and said:" You are the only man who touched me, after we broke up, i never find a new boyfriend until i met you again."
Then my ex became my new one, but we are not in the same city, we can only call each other every day or send mails,sometimes we also chat on MSN.
Then trouble came, yesterday when i chat with her, we talked about the summer vacation, she said she already bought air tickets and wanna fly to China to see me again ,then we talked a lot about sex, i told her it feels better without wearing candom when we make love. She said she got an idea, i asked what idea? She said she can use the oral contraceptives and she still has 17 pills left which she bought 2 years ago(PS: when she said that, she acted very happy and noraml). Then i was shocked, but i didn't ask her anything even i felt very strange.
I do trust her, So i believe what she told me before, But now what she told me is paradoxical. I don't care her past, but i do care if she lied to me. I haven't told her about my feeling yet. I am afraid it will makes her to feel i did not trust her.
I don't know what to do now, shall i tell her about my feeling?
PS: Sorry about my english level, I am not native speaker.