You're addressing your own or someone else's disorder/illness, no matter if it's physical, mental, or emotional. Treat it like another person and just get it off your chest. It's something I did once in Group a while back, so if you think it'll help, give it a try~
Dear Anorexia, I hate what you did to me and my family. You promised me control, when really you took it all away, torturing me with your pointless rules. The people I care about watched me dance with death, and it will take years to regain their trust. But that's OK, because it's years better spent than the ones I spent with you. No longer your slave, Whisper.