Donacien has not been playing as much as he wanted, which led to his desire to move.
He is signing for League Two Chesterfield, where his former Town manager Paul Cook is in charge.
“I think this is the hardest goodbye I’ve ever had to say,” Donacien told TownTV.
“I don’t really want to say goodbye, I always try to say, ‘see you later’ because ‘goodbye’ means you’re probably never going to see someone again, so I’ve just tried to keep it nice and hopefully I do see most of the people again.”
Donacien reflected: “High points, extreme high points, signing, extreme low points and then just extreme highs again, just riding the wave of football.
“I’ve seen pretty much everything that’s happened here. On the inside and from outside because obviously I left to go on loan. I’ve seen pretty much everything.”