The experienced coach enjoyed six productive years in the St Andrews dugout before breaking ties with the Blues in November 2007.
His relationship with the Birmingham board had become untenable by then, with a promised new contract failing to materialise as the club became embroiled in a distracting takeover saga.
Bruce opted to take on a new challenge at Wigan, and has since moved on to Sunderland, but he will forever be troubled by the events which accompanied his departure from the Midlands.
"After so long, eight years, I felt very let down, and still do, and always will," Bruce said in the Daily Mirror as he prepares to head back St Andrews on Saturday with his latest employers.
"Then there was David Sullivan saying getting rid of me for £3m was the 'best piece of business the club had ever done' - thanks a lot!
"Washing the dirty linen in public like that shouldn't have happened, I deserved better than that.
"I had every right to be all bitter and twisted."
VulnerableBirmingham have recently been bought out by Far East businessman Carson Yeung, but it was his efforts to take charge of the club in 2007 which led to Bruce's demise.
The Black Cats boss admits as much and accepts that he should have walked away from the Blues before the turmoil was allowed to set it.
"Dead man walking, that was me," he said.
"There were broken promises and for everyone it was very, very difficult to actually concentrate on what mattered: the football.
"There was takeover talk all the time and whether or not Carson Yeung could come up with the money.
"I was vulnerable and everything filtered through to the players."
Bruce added: "In hindsight, maybe I should have gone after relegation 2005 but I didn't want to leave the club in the Championship, so I stuck it out and we got promotion."