Harry Miller's football career is over -- the Ohio State lineman is medically retiring from football ... after revealing his mental health battle was so bad at one point, he contemplated killing himself.
Miller -- who started 7 games at left guard for the Buckeyes in 2020 -- released a lengthy statement to Twitter on Thursday ... addressing why he's walking away from the sport.
“Prior to the season last year, I told Coach [Ryan] Day of my intention to kill myself," Harry wrote.
The junior player said Day took the conversation seriously .