She admitted: "There was a quote on the wall as I was leaving the exhibit it said something like, 'Becoming a father is the best thing that's ever happened to me'.
"I'd never see it before. It kind of reinstates what I felt was the truth, which is that. I felt like I was the most important thing to him. He would protect me. That's the protection I had and ever had, especially recently, that he'd absolutely protect me."
Lisa is planning to write an autobiography in the near future, which will document her childhood and her relationship with Elvis, but she's busy doing fiction at the moment.
She said: "I will absolutely do one. I just don't know when.
"I haven't had time to think about that. I'm still in the middle of a psychological thriller right now, when it's over maybe I can write it."
The brunette beauty's 29-year-old daughter Riley Keough - her child with Danny Keough - has followed in her grandfather's footsteps and carved out a career in showbiz but Lisa would have never let her pursue it if she wasn't intelligent.
She said of Riley: "I felt like Riley had a really good head on her shoulders. If I had a child that did not, and didn't seem to be strong in themselves, I wouldn't allow it.
"Riley was absolutely like, 'I'm going to model for money and then I'm going to act, and then I'm going to be a director'.
"She had a plan and did everything she said she was going to do. I wouldn't do that though if I felt there was uncertainty or vulnerability or a weakness, I'd have them home until 18."