04/05/2011 at 06:25 PM EDT
In a raw new memoir, All That Is Bitter & Sweet
, Ashley Judd is baring all when it comes to being raised as the daughter of country music's Naomi Judd.
"My childhood was erratic, chaotic, unstable," she tells PEOPLE in this week's issue. "I was so the lost child, who just goes away and can be invisible while sitting in the middle of the room."
"I know that my mom did the best she could as did my dad," Judd, 42, continues, "but for a variety of reasons, it was just hurtful."
Judd would attend 13 different schools from ages five to 18, while her older sister Wynonna built a country music empire with their mother. She began to suffer from depression, which led to suicidal thoughts, and she has memories of sexual assault from various men over the years.
"The abnormal becomes normal," she says. "Perpetrators are shameless, and they put their shame on their victims."
In 2006, Judd elected to enter treatment
for her depression at a rehab facility in Texas. "I would have died without it," says the actress, who married racecar driver Dario Franchitti
in 2001. "It has improved my life on every level."
Judd also channeled her anger and grief into her passion for humanitarian work as a YouthAIDS ambassador
for Populations Services International. She has traveled to more than four continents in the past seven years advocating grassroots programs to improve the lives of women and children.
"Our painful past becomes our greatest asset," she says. "Now I can look at it and say, 'Wow, that shouldn't have happened to a dog much less a child.' "
For more of Judd's interview and exclusive photos, pick up this week's issue of PEOPLE, on newsstands now.