first thing first, how open she is?

If she is open to these concept, you might able to tell her and not freak her out. But just like other love story, you might get rejected.

IF she is traditionalist, then just move away and forget about it.

Firstly, you are at a crossroad. Not telling her, you have to deal with all the feelings you are having, and it is only going to be time before they take over you and blurs your judgement. Telling her might cause her to steer away from you (or at least i think that is how you feel it would go down). Which means rejection towards your honest feelings, leaving you vulnerable and broken. That fear itself is causing you to have doubts. We've all been there. Every single one of us at some point.

Your situation is very similar to a kid sitting by the piers with the doubt of either jumping into the river or not. Tough decisions to make and all. But you have to be the judge of it. If i were in your shoes, i would tell the girl. Why? Because why not? Keeping it in is never good. Too hasty and it all goes to hell. Just tell her in your most honest words. Sit her down somewhere and talk to her. Refer and relate to her as a person, not as an object of your desire.  Tell her all that you've been keeping in. Share with her how it makes you feel. Do not expect her to reciprocate your feelings. Most people will freak out. Expect that. But it is not something unheard of to have feelings for the person who you associate as same sexuality as you.

Then, allow time to let her sink all that details and information into her thoughts. Do not rush her, and let her judge and decide by herself. It is a good practice to leave telling her your feelings as a heartfelt "heart to heart" talk. Instead of a confession of guilt, that by having feelings for her is wrong. (which sadly most guys of malaysia seems to do). Then go on your life like normal with her. Don't try to treat her any different, in the hopes of it helpign your agenda. She will show you how she will deal with your feelings in due time. But the most important thing is to tell her, let her digest, and react with her reaction. And don't be disappointed if she rejects you. Take it as an experience worth learning.