Korn Frontman Jonathan Davis Speaks Out About Wife's Death & Mental Illness

Jonathan Davis says his wife Deven was very sick for the past decade, and suggests her mental illness led to her addiction ... and it's to blame for her death.

Korn's lead singer shared a message on Instagram Wednesday night to address what happened to his estranged wife. He said, "Over the past decade, my wife has been very very sick. She had a serious mental illness and her addiction was a side effect. I loved her with ALL of my being."

He goes on to say Deven was an amazing wife, mother and friend ... and he tried for a long time to hide what was going on with her in order to protect her.

Davis says Deven's the reason he has advocated so passionately for people struggling with mental illness, and hopes her story will help inspire change. He also mentions their 2 children, saying ... "I promise I'll do everything in my power to raise our precious boys the right way, teach them the good values you wanted them to have so badly, and break the cycle of abuse we both experiences as kids."

We broke the story ... Deven died Friday, and the news came on the heels of Jonathan's request for a domestic violence restraining order on her. Jonathan alleged Deven was deep into drugs and her drug use was causing emotional harm to their 2 sons.

According to the legal docs, Deven had been in a sober home but went AWOL a week before she died.