Be honest, bottom line, be honest with her and with yourself. I think most people would pick honesty over some guy trying to be overly masculine or macho and struttin' his stuff. If she's truly your friend and is interested in you, she'll respect your honesty. It's okay to take things really slow. She may have her own insecurities she's dealing with that you're not aware of.
If you feel comfortable in sharing with her that you don't want to blow the friendship and what it can blossom into, then do so. The most important thing here is to be yourself. Don't know if any of this helps, but honesty and respect is the best foundation for any relationship.
It's hard to be in a lopsided relationship, where one person feels more for the other than visa versa. Sometimes time is all what's needed and eventually the two are on the same page.
From the sounds of it, you're in the beginning stages of a friendship that has a possibility of becoming serious - right? If so, take your time and be honest with your feelings
Einna