Alphonso Smith Jr. — a former NFL player and standout cornerback at Wake Forest University — has died … TMZ Sports has learned.

Sources with direct knowledge tell TMZ Sports … the former cornerback died by suicide on Wednesday at a housing community in Florida.

Alphonso’s final Facebook post highlighted his unstable emotional state before his death.

In the post, Alphonso wrote, “Do not cry for me! I tried everything in my power to fight the demons behind the ones that someone put into ME! I did not want to be that WAY! I know I have disappointed so many folks. This is a DEMON in me! But not only me! It’s EVERYONE! I have HURT so many! I needed help & did not get it!”

He repeatedly apologizes in the post, calls himself a “coward” … and includes a reference to some abuse suffered at the hands of an older woman when he was a young boy.

Alphonso ended the post by writing, “I am SORRY! THIS IS IT!”

Alphonso attended Wake Forest from 2004 to 2008 … earning All-American honors in his final season with the school. He was inducted into the school’s athletic hall of fame in 2022.

He was drafted by the Denver Broncos in 2009 — though they traded him to the Detroit Lions just one year later. He played 3 seasons in Detroit … ending his career after the 2012 campaign. He recorded 88 tackles and 8 interceptions across 42 NFL games.

Alphonso was 40 years old.

RIP