The R&B singer left the quartet in 2003 due to chronic back problems, and he revealed for the first time on U.S. TV show Iyanla: Fix My Life on Saturday night (29Oct16) the autoimmune disorder was the reason behind his departure.

The 44-year-old explained, "I was in Boyz II Men when I saw some of the ailments start to happen. It was like little back spasms at first, and then they would get stronger and stronger. Each time it would get more harsh... Once I was about 22, it started going to full-scale.

"They (doctors) were saying that I have a nerve around the sciatica that was locked in place that could sever if I stepped wrong, saying, 'It’s a possibility that you could be paralysed.'"

He told other guests on the show his condition, which affects nerves in the brain and spinal cord, sent him into a depression.

TV host and life coach Iyanla Vanzant said in a voiceover she believes MCCary’s decision to keep his health battle a secret "proved the most dangerous" and adds that he hasn't even told his old bandmates Wanya Morris, Nathan Morris and Shawn Stockman, who MCCary claims abandoned him when he became ill.

"I want to get over the hurt and abandonment that I feel from the group that I’ve been with for so long and gave my life to," he said. "I want to be able to go in a room with them and not feel like I want to choke them."

His revelation comes just weeks after the bandmates spoke about his departure on TV show Oprah: Where Are They Now? when Wanya claimed MCCary's back issue could have been fixed but he just "stopped coming to work" so they decided to continue without him.