By Jeff NelsonOriginal Source: people.comIn a heart-wrenching new memoir, Dianna De La Garza, mother of Demi Lovato, opens up about her family’s battles with mental illness and addiction — and her famous daughter’s tortured path to success.“I wanted to share this story because I thought there might be people out there who might be going through some of the same things that my family was going through,” Dianna, 55, tells PEOPLE of her book Falling with Wings: A Mother’s Story (with Vickie McIntyre). “It might help them in some ways.”Over the years, Demi, now 25, has been open about her struggles with bipolar disorder, bulimia and substance abuse...click here to continue reading