I would try to keep it short and to the point. If you want to have a positive outcome with this opportunity with your WAS, I doubt making a reply about you and your feelings is going to achieve that goal.
My response would be:
Thank you for the honest, heartfelt note. After re-reading this several times, I do see your point regarding my actions lately. Can we get together to discuss these concerns and maybe clear them up?
If he/she's receptive, then when you do meet, LISTEN and respond accordingly - this is about their concerns.
Unless I'm completely wrong in what I've been reading, DBing is about what you can change about YOU to be a better person. The changes in those around you is really their reactions to what you change about yourself.
