Kristoff St. John was found dead in his San Fernando Valley home on Feb. 4

Kristoff St. John‘s ex-wife Mia St. John is speaking out on the last conversation she had with the Young and the Restless star before his sudden death.

“He called me at 11 a.m. and the first thing he said is, ‘Oh Mia, thank God you answered,” Mia, 51, tearfully told Entertainment Tonight of speaking to Kristoff on the morning of his death on Feb. 4.

“He was just so depressed. We knew he was drinking and just saying he didn’t want to be here anymore,” Mia, who married St. John in 1991, explained. The former couple split in 1995 but remained close.

Mia then told ET that St. John was disoriented and told her that he saw their late son Julian St. John, who died by suicide four years ago following a lifelong battle with mental illness.

“‘Julian’s at the door,'” Mia recalled her ex-husband telling her over the phone.

“[He] said, ‘Okay, let’s talk to Julian, bring Julian in,'” Mia said St. John told her to Entertainment Tonight.

“Julian came in and he said, ‘Julian is gonna take me for a walk now’ and I said, ‘No you aren’t going for a walk right now,'” Mia told ET.

Shortly after, St. John was found dead at his home in San Fernando Valley after one of his friends went to check on him.

Kristoff St. John and Mia St. John
| Credit: Ron Galella, Ltd./WireImage

“They found him on the floor. They tried CPR and he was already gone,” Mia told ET. The actor was pronounced dead on the scene. He was 52.

In addition to their phone call, Mia says she and St. John were “texting back and forth that day.”

“He said, ‘Understand, you’ve got to live in the present. Observe all the good things in your life and others around you. Julian would not want you to live your life with bitterness and upset,'” Mia told the outlet, sharing her ex-husband’s final words.

Mia went on to explain that their son Julian’s death took a toll on St. John.

“When Julian passed… he literally died of a broken heart. Kristoff suffered from bipolar; our son had schizophrenia. I just felt like it was just hard to get people to pay attention,” Mia explained to Entertainment Tonight.

The deaths of her son and ex-husband have pushed Mia to raise awareness on the struggles of mental illness.

“I have never been so determined to change how we treat the mentally ill in this country. I give you my word that my fight is never going to end. I’m going to make my boys proud,” Mia told Entertainment Tonight.

Julian St. John and Kristoff St. John
| Credit: Julian St. John/Facebook; Robert Voets/CBS/Getty

According to a 2013 Huffington Post profile, Julian, an artist, was diagnosed with schizophrenia at the age of 18 and had endured bouts of severe depression since he was a child.

“Our son was the light of our lives, an artist with a beautiful mind and spirit,” said Mia, who went on to found the El Saber es Poder (Knowledge is Power) Foundation to battle mental illness, in a statement at the time. “He fought long and hard against an illness for which there is no cure. Unfortunately, the pain became too great for him and I dare not say he lost the battle — he simply chose to set himself free. My fight for mental health will continue. They may not find a cure in my lifetime, but we can try and prevent the loss of another beautiful soul.”

Two weeks before he was found dead, St. John mourned the loss of his son on Twitter.

St. John was last active on the social network on Jan. 21, when he retweeted someone’s post about losing a child that reads, “Grieving the loss of a child is a process. It begins on the day your child passes, and ends the day the parents join them.”

“Never a truer word was spoke,” St. John tweeted. “Thanks for posting this.”

The Los Angeles County Medical Examiner-Coroner confirmed to PEOPLE on Monday that St. John was found dead at a home in Woodland Hills on Sunday. He was pronounced deceased at 4:02 p.m.

According to the Los Angeles Police Department, a death investigation took place at around 2:05 p.m. for a possible alcohol overdose at the 2300 block of Morea Way.

Kristoff St. John
| Credit: Renard Garr/Getty

St. John is survived by his fiancée, Kseniya Mikhaleva, as well as daughter Paris with Mia and daughter Lola with ex-wife Allana Nadal.

On Feb. 6, Mikhaleva opened up about the heartbreak she’s experiencing as she mourns St. John.

The Russian-born model posted a photo of black tears coming out of a woman’s eye alongside a heart-wrenching short poem.

In the overlying text, she shared the words, “My hands they shake with sorrow, My heart it bleeds with pain, My soul forever lingers, Wishing you could have stayed.”

If you or someone you know is considering suicide, please contact the National Suicide Prevention Lifeline at 1-800-273-TALK (8255), text “home” to the Crisis Text Line at 741-741 or go to