Naya Rivera's Dad Reflects on Her Legacy and Shares His Heartbreaking Father's Day Letter to Her (Exclusive)

The actress' father shares what he wants people to know about the late 'Glee' star.

Naya Rivera's father, George Rivera, says Naya wasn't done yet when it came to accomplishing what she wanted to before her tragic death last July.

ET's Kevin Frazier sat down with George for an emotional conversation ahead of his first Father's Day without Naya, and he opened up about her legacy. The Glee star was pronounced dead on July 13, five days after she went missing at California's Lake Piru while taking a boat ride with her now 5-year-old son, Josey. She was 33 years old.

George shared what he wanted people to know about his late daughter. He noted that Naya was tough, yet also vulnerable, and always stayed true to herself and remained thoughtful when it came to using her platform to help others. For example, Rivera was a big supporter of the LGBTQ community, hosting the GLAAD Media Awards twice.

"It's about sort of the strong dynamic personality and never giving up," he says of Naya's legacy. "Never giving up on your dream and your focus. It's what I'm trying to teach all her Twitter followers, the joy that she had in life, right? The joy that she had and living the life that she lived. She knew she was lucky, but she knew she worked hard for that."

"You know, my mantra with my kids had been about that and maybe that's really myopically focused but you try to teach your kids how to navigate life," he continues. "And how to have a little bit of a hard skin too when you get rejected. And to be who you are, right, not to try to be someone else. You know, she didn't go off and try to be that character [Santana from Glee]. She tried to be Naya and show people the best that she had -- always happy."

George shared with ET a heartbreaking letter he wrote to Naya ahead of his first Father's Day without her. The letter reads in part, "Your beautiful son Josey is strong, healthy and happy. He's growing up and being taken care of just like you did, he knows you're OK and watching over him, rest assured. And he talks about you all the time, Mama. Thank you for caring for me, your brother and sister. Keep sleeping soundly my angel, and we'll take it from here. I love you and miss you, but I know you know that. Love, Dad."

George explained parts of his emotional letter.

"She didn't finish what she started in terms of what she wanted to do with maybe her voice, her platform, with her talent, with her skill set, but I wanted her to understand I feel that connection with her and I wanted her to understand that we're not only OK, we're gonna take on the challenges of life and the challenges of helping raise my grandchild, your child, with the same sort of satisfaction, vim and vigor that you had," he notes.

The father of three candidly talked about his relationship with his daughter, including a period when they didn't see eye to eye. But before her death, he said their relationship had evolved and they were planning to collaborate on new music together.

"We had a really good relationship," he says. "You know, father-daughter relationships always go sideways, maybe it's from the advice you give them, but, you know, as they're growing up, they're listening to you and at some point it's like, 'Really, what do you know?' And those are the dynamics we had to overcome and I think we overcame that really well into a respectful friendship, partnership. She always came back to me about maturity things that she needed to learn about when she started having a child, that was a big moment."

George also talked to ET about the devastating days surrounding the search for Naya, including one particularly emotional moment when he jumped into Lake Piru.

"That moment I needed to reconnect with the water," he recalls. "I needed to reconnect to where she was and my number one goal was finding her. And I did not know how to do it other than just getting into that water and having a moment. ... Because at that moment we had really little hope on what happened, how it happened, and if we were going to find her."

George is now doing his best to come to terms with Naya's death. He shared that he couldn't even look at pictures of her for nine months following her tragic drowning.

"Trying to look at intimate pictures is really difficult," he acknowledges. "You know, it's just the human spirit. You really don't want to come to terms with things like that, a big lesson here is .... reality makes you come to terms with it and each one of us has to find out how to come to terms with it, so it's a management process rather than 'I'm over it.'"

"It's like losing a best friend, it's like losing the people that are most close to you," he adds. "You're not gonna focus in on any kind of tragedy or any kind of end to the story, you’re gonna focus in on the good life that you had with them or the robust times that you had with them. That would be my only advice. No one's prepared for this."

He says he is using this Father's Day to continue to remember Naya's extraordinary life and legacy.

"Well, I think Father's Day is going to be really special because we are going through this process, this is allowing me to grieve in terms of vocalizing our relationship together, so it's a lot easier," he says. "So, I will go through this Father's Day knowing and being prideful that I think I did a good job raising a child."