Ex Problems

Okay, here is the short story. I have this ex-girlfriend that is still kinda my friend. Well she has started e-mailing me telling me that she still likes me...A lot. And she keeps asking me if I like her more than my girlfriend which is really starting to piss me off. I am the type of person who has a hard time hurting people's feelings. Can anyone tell me the nicest way to tell her to stop asking me that and that I just want to be friends with her...Oh yeah and to never bring up the fact that she still likes me ever again. I know it my sound kind of mean but I have moved on. She hasn't and she needs to understand that I am with someone else now and that it is her fault because she dumped me...Help?