The dual All-Australian called it quits in March, exactly two weeks before the Demons' campaign began under new coach Steven King.
"The worst part about it was I had just done a pre-season, and I hate pre-seasons," May told SEN on Wednesday.
"Some people love them, but I really hate them.
"It was the end of January so I'd finally got through it and was ready for a new year, I was injured all last season and had a bad year on the field.
"I was really ready to show people that I still have it, did the pre-season, ran a PB in January, up and about, let's go.
"Then I had a bit of a mental breakdown and found myself a bit lost and not sure what to do.
"It came to a point where I had to put the club before myself.
"I was able to retire before the deadline so then they could get another player in ... all in all it looks like it's worked well for both parties."
His comments come less than a week after all charges were dropped against May and Richmond premiership midfielder Dion Prestia.
The magistrate also ordered the legal costs of May and Prestia be paid by the Chief Commissioner of Police.
"Your name gets dragged through the media. I know I don't have the greatest name already, so that didn't help," May said.
"Especially when you were so innocent in something.
"You can't really do much or say much because it's a criminal charge."
May, who famously played in Melbourne's 2021 grand final win with a torn hamstring, is playing local football this year with East Ringwood.
"There comes a point where you've got to make a decision that's best for my family but also for the footy club," he said.
"My family is happy and the club is flying, so I'm pretty stoked with it."
May played 128 games with Melbourne and 123 for Gold Coast, where he was also co-captain for two seasons.
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