Ric Flair shared a heartbreaking farewell to his stepson, Sebastian Kidder ... saying the 24-year-old musician was "Multi-talented & in everybody’s eyes a huge success and will always be remembered that way."
The wrestling legend broke his silence after Sebastian's death ... explaining he unfortunately understands the agony of losing a child -- as his son, Reid, died of a drug overdose in 2013.
"I know the pain of your loss will be with you the rest of your life," Flair directed to Sebastian's parents, Wendy and Paul.