Singler, 36, spoke slowly and was shirtless in the short video, which was posted Tuesday morning.
"I have been mistreated and abused, neglected, made into a mental example," Singler said. "And I fear for my life every day. And people in my community make me look out as if I'm going to be someone that's going to be a problem and make things difficult for people when I'm only trying to be helpful.
"I feel like I have a certain way about myself and strength and purpose that does not get valued or get treated properly."
The video cut off abruptly after about 90 seconds. It was shared more than 1,200 times in the 12 hours after it was posted.
Several NBA players responded.
Kevin Love of the Miami Heat wrote, "I love you, Kyle. Hit me whenever. Please."
Veteran guard Isaiah Thomas said: "Here for you bro! Always and forever."
Philadelphia 76ers center Andre Drummond added, "You aren't alone brother! I'm here for you."
On Wednesday, the National Basketball Players Association said it had connected with Singler's family.
"We are in contact with Kyle's family," Sarah Houseknecht, a spokeswoman for the NBPA, said in an e-mail to The Associated Press on Wednesday morning. "As with all current and former members of the NBPA, we offer any and all support to players, whether through their biggest successes or times of challenge."
Many of those who responded included Duke men's basketball and the NBA in their comments, hoping to get their attention.
Singler was on Duke's 2010 national championship team and was named Most Outstanding Player of the NCAA tournament.
He posted another video Tuesday afternoon. He repeated grievances from the first post but seemed more stable.
Singler was the 33rd overall pick in the 2011 draft and started his career overseas before playing in the NBA. He played three seasons for the Detroit Pistons, who drafted him and was on the All-Rookie second team in 2013. He played parts of four seasons for the Oklahoma City Thunder.
ESPN and The Associated Press contributed.
This story includes discussion of suicide. If you or someone you know needs help, the national suicide and crisis lifeline in the U.S. is available by calling or texting 988. There is also an online chat at 988lifeline.org.