"I went out of my way to deal with myself and just be there as a symbol of strength and happiness for her," Patton Oswalt tells PEOPLE
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Patton Oswalt and daughter Alice
| Credit: Meredith Salenger/instagram

Patton Oswalt is opening up about how he and his daughter Alice Rigney coped with the death of his first wife.

The actor and comedian, 51, married true crime writer Michelle McNamara in 2005 and welcomed Alice four years later. McNamara died suddenly in her sleep in April 2016 at age 46, from a combination of prescription medications and an undiagnosed heart condition.

Oswalt has since remarried, tying the knot with Meredith Salenger in November 2017.

"We just were very, very honest about, 'Here's how I'm feeling,' " the father of one, 51, tells PEOPLE for this week's issue leading up to Father's Day of how he and Alice, now 11, dealt with McNamara’s death.

"Although I made sure that a lot of my darkness and sadness I went through without her seeing it, only because she's already suffered this blow by losing her mom, I don't want her memories of me to be of a parent that's despairing even deeper than she is," Oswalt continues. "I don't think that's a good foundation to grow up on, so I went out of my way to deal with myself and just be there as a symbol of strength and happiness for her."

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Michelle McNamara, Patton Oswalt
Patton Oswalt with his late wife Michelle McNamara
| Credit: Gregg DeGuire/FilmMagic
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Patton Oswalt and daughter Alice in 2019
| Credit: Dan MacMedan/Getty

Oswalt, who is featured in the new AppleTV+ documentary film Dads, also shared that one of his proudest moments as a dad came after his first wife's death, when his daughter said something that hit him as especially poignant.

"We were in despair for days and months afterwards and then one night we were up and neither of us could sleep," he recalls. "We were just talking and trying to get through it and my daughter just said, 'When your mom dies, everything you do is a memory of her. You are a memory of her. You are her memory.' "

"It just came out of nowhere and I was like, 'Oh my God,' " Oswalt adds. "I remember very specifically running and writing that down."

Patton Oswalt with wife Meredith Salenger and daughter Alice
| Credit: Jen Lowery/SilverHub/Shutterstock

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Now, Oswalt feels that he and Alice have "made it through the darkness" and his daughter has been able to bond with Salenger, 50. The pair watch The Office together (Alice is "obsessed"), go swimming and work on crafting projects.

"[Meredith is] just always trying to work on stuff with Alice, which is great," Oswalt says.

Dads, directed by Bryce Dallas Howard, is playing now on AppleTV+.

For more from Patton Oswalt, pick up the latest issue of PEOPLE, on newsstands now.

By Mia McNiece and Ally Mauch