how to say "i love you"to a girl that i like very much

I know it is not easy ,but if I don't ask you to be mine ,i will be regrest in the rest of my life cause i know ,in my heart you are the only one for me 我知道那样不容易,但是如果我现在不告诉你,我的余生会充满后悔,因为我知道,在我内心深处,你是我的唯一