Caitlyn Jenner is "much happier and freer in her feminine self".

In an excerpt from Linda's memoir A Little Thing Called Life, obtained by PEOPLE magazine, she writes: "Caitlyn seems so much happier and freer in her feminine self ... I sometimes find it surreal to look into her perfectly made-up, beautiful brown eyes, while remembering the masculine, gorgeous man who fathered my sons. I completely accept, respect, and support Caitlyn, but I must admit, I sometimes miss Bruce."

Meanwhile, Linda - who has Brody, 32, and Brandon, 35, with Caitlyn - previously revealed the 66-year-old television personality planned to have a secret gender transition in 1985.

She shared: "As we tried to work through our feelings. Bruce told me he was considering traveling out of the country, possibly to Denmark, to try to have the gender reassignment surgery anonymously and then come back as a female. He thought maybe he would reenter their lives as a female relative. He was grasping for a lifeline. As devastated as I was, my heart bled for Bruce.

"I felt such an obligation to keep Bruce's gender dysphoria his secret that I did not even tell my sons until they were 31 and 29 years old, respectively. I wanted them to experience enough life and garner enough knowledge, confidence and compassion to be able to deal with their father's true self."