How to choose?

I recently met an awesome girl and weve been dating for about 3 weeks, I know its still really soon, but im really happy with her...the problem is that, 2 days ago, the girl that I always wanted to be with, finally told me her feelings and basically said that she wants to have a relationship with me...3 weeks too late unfortunately =[
What do I do? We have an awesome friendship relationship for more than 2 years, but I've always wanted something more than just a friendship..when I gave up on trying, I met this other girl who im now happy with...now what??!? Is it worth taking the risk and break up with the girl I recently met and who im happy with, for the girl that I've been wanting to be with for the past 2 years?!?

I think at the end of the day, you have to search deep inside yourself for the answer to this question. All we can do here, maybe, is give you a few things t think about, lol.

What if you leave your current girl and then it doesn't work out with the one you thought was going to be the romance of the century? Would you go back to the old one with your tail between your legs?

Is it possible you have some time to make this decision? IF you do have time, will it strain your existing relationship because you're always thinking about the other?