Geno tells TMZ ... he tried to kill himself back in September by chasing 90 blood pressure pills with a liter of Jägermeister while at his Florida home.

He says he was feeling down over everything going on in his life, explaining he had been miserable for a long time leading up to the attempted suicide.

It's interesting ... that happened right around the time he and Mama broke things off, but Geno told us that wasn't the reason he tried to kill himself. Watch the video ... he says it was the cumulative effect of untreated issues that began before June.

Luckily for Geno, a friend was at his house the night he popped all those pills and noticed the empty bottle. He says she called 911 and paramedics ultimately saved his life. After that he ended up in a mental health facility ... and when he was released, June offered a helping hand.

The way Geno tells it ... June came over to pick up some of her belongings, and when he told her about the OD, she referred him to a rehab center in South Carolina.

Since going through treatment, Geno says he's been going through the 12 steps and learning a lot about himself, and what put him in a "dark place."

It sounds like Geno's doing a lot better now -- but explained why he's no longer in touch with Mama June.