It does not sound like the woman you're thinking of waiting for thinks of you the same way you think of her. If she's re-writing history in your view (ie calling the relationship more like brother sister than lovers) there's a reason for that. I don't know what age the touching and the sex started but maybe she does feel that she was taken advantage of. I am very confused, you say it was a secret yet your mother and best friend (her brother knew) the relationship was secret from whom? And more importantly, think WHY you felt the need to keep it secret.

We've all had a relationship with a "what if" involved. It's been my experience that the reason it didn't last was because it was not to be. You're not being fair to yourself nor your family. Right now it sounds like you're using this fantasy perfect relationship as a crutch. It sounds very much like she's been trying to tell you for quite some time that this relationship is not for her but you don't want to hear it. So what happens if she decides not to respond to your letter? Will you let this go?

On a side note, coming from a long line of alcoholics, not remembering things you've done or said while you're drinking is a dangerous sign.

I wish you all safety and contentment.