Barry Hawkins revealed the death of his brother-in-law "absolutely destroyed" him after booking his place in Sunday's Welsh Open final against John Higgins.
Hawkins, beaten finalist at the 2013 World Championship, defeated Thailand's Noppon Saengkham 6-4 in Cardiff, while four-time winner Higgins overcame Gary Wilson 6-2.
It is the first time this season Hawkins has gone beyond the last 16 of a ranking event and the 38-year-old gave a moving explanation for his loss of form.
"Last April I had a belated birthday party with the family after the World Championship," Hawkins told World Snooker's official website.
"For the previous six months my sister's husband had been suffering from depression. We all thought he was getting back to normal.
"That evening he was dropped at home by my dad. Sadly he took his own life. He felt like there was no way out for him. We didn't see it coming at all.
"I was with him for an hour while the paramedics were working on him. I have never experienced anything like that and I wouldn't want to go through it again. It absolutely destroyed me for about six months.
"I played snooker but I really wasn't thinking about the game, my mind was elsewhere.
"It was very tough for my family and especially my sister and her two twins, who are eight years old now.
"It was devastating, so snooker had to take a back seat. In the last few months I have been trying to find my form again.
"I feel better about myself and we're moving on. We'll never forget what happened, but at least we are dealing with it now."
Victory on Sunday against Higgins, who knocked out Ronnie O'Sullivan in his quarter-final, would seal Hawkins the £70,000 winner's prize and his place at the lucrative Players Championship in Llandudno later this month.