Sylvester Stallone is finally speaking about the death of his son Sage ... calling it a "horrible situation ... but it's something that is reality in life."
Stallone just appeared on "GMA" to promote his new "Expendables" movie ... when the reporter asked how Stallone was "hanging in there" since Sage passed away last month.
"It's tough it's very very tough," Stallone said ... adding, "But if you have good friends and your family’s support, it's just something that’s a horrible situation but ... hopefully it will heal and you try to get through it but it's something that is a reality in life."
Stallone noted that working on his new movie has helped him get through it ... saying, "It's important to get back and try to start reliving your life, otherwise you can go into a spiral."
Sage -- who starred in "Rocky 5" with Sly -- passed away on July 13 from an apparent drug overdose. He was 36.