It was a moment Kimberly Williams-Paisley never thought she'd have to experience: the day she stopped recognizing her own mother.

Diagnosed with dementia in 2005, Kimberly's mom Linda quickly became "a fading picture of who she used to be," the 42-year-old wrote recently in an emotional essay.

"I resented this mostly manic, dangerous, crazy woman who had taken over my mother's body. I hated her insidious disease."

The brain disorder, called primary progressive aphasia, is life-changing for those diagnosed – and the family members who are left to face its harsh realities.

"She had falls that landed her in the ER," explained the actress. "It was scary and exhausting."

But the wife of country star Brad Paisley says she has come to find "a kind of healing" with her mom's condition.

Whether rubbing lotion on withered, familiar hands or humming "You Are My Sunshine" together, Kim and Linda now enjoy a relationship neither could have foreseen.

Writes Kimberly in her Redbook essay, "She and I discovered a new way to say, 'I get you. You understand me. We love each other.'"