Graham, not much to add to everyone elses post except a bit of advice on dealing with unstable people (had manage a few in my time).
1. Phone calls only & keep them brief. No emotional content. Say what you want, suggest how to get it, say thanks and hang up.
2. NEVER put anything in writing anywhere you aren't prepared to have posted on the NY Times website. Seriously. Even the internet is less anonymous than you think.
"Spoken words are gone with the wind. Written words are forever."
If you do write, its business only.
Second thoughts can generally be amended with judicious action; injudicious actions can seldom be recovered with second thoughts.
--Cyteen by C.J.Cherryh