Her e-mail to me before she left for a vacation:

ok, before I head to the airport, I just want you to know that I wasn't really mad at you, I was mad at myself. You probably think I am wasting your time, I could've just say no when you first asked me out. The thing is, I do like you, but even if I said yes, I know the relationship won't last. I really wanted to be that kind of girl who can just forget about the future and live at the moment. But when you popped up the question, I still said no, so maybe deep down I just still couldn't be that kind of girl. I couldn't bear the idea of dating someone when I know I wil get hurt later on.
So...if you don't want us to be friends, it's ok, and it's probably better this way.
And I can't get access to the facebook while I am out of town, so...
Anyway, have a great holiday!

What is the best way to reply?

The thing is that she told me no for a relationship, and I kind of left her to go back home by herself [bad I know] and she e-mailed ME saying she was sorry to be mad, which she had every right to cause I left her to head back home in the middle of the night.

She said that she was ok with being with being friends if I wanted to I replied "No, I have lots of friends. See you later." to which she replied "What?!" then I didn't reply then I got this..I replied "It could last...I wouldn't any invest time/energy if it couldn't...bye"