I'm glad to hear that she responded to your letter! I'm sure it felt good to hear from her...
I wish I could give you some sort of advice on how to respond....sorry
I'm on day 19 of not hearing from my H and I don't know what I would do if he actually contacted me.
M: 27 H: 28 T: 8 yrs M: 6 yrs Sep: 2/18/12 (I have no feelings for you!) EA/PA Uncovered: 2/26/12 H introduces OW to his fam: June H moves ALL stuff out: July