I think it's very common to think could I have done more Ken - in my experience tho if someone has decided that's what they want to do they'll withdraw and not have much contact with anyone.
OI know you as a pretty stand up guy and I know you would have gone beyond what was expected of you to help Sherri out over the years.
I think Toots hit on something too - I think Sherri chose that day because it meant something to her still.
This is a pretty good thread to read Ken
http://www.soberrecovery.com/forums/...y-what-if.html