Well I have been best friends with her since a month after we met and she always dates douche bags. And I got friend zoned and we are best friends and we love each other but now that we both like each other the dating way. She is afraid of messing up our relationship and losing me. I know that she would never be able to mess this up, and I need help trying to convince her how perfect we are for each other.

You let her go at her own pace, decide things her own way. She could be right.

There is nothing to convince, or confess. Have fun dating and see how it goes.