is opening up about what led to the end of her marriage with .

During the first episode of her new podcast , the  alum, 50, addressed her recent decision to from her estranged husband, sharing that their marriage hadn't been the same since they started to have kids.

The former couple is parents to Beau, 7, Finn, 11, Hattie, 12, Stella, 15, and Liam, 17.

"When I got pregnant, we got pregnant right away. So we got married in May, and we started trying right away," Spelling shared, adding that she got pregnant shortly after her dad passed away.

"Basically I conceived right after my dad passed. So I took that as like, 'Oh, it's a sign.

This is supposed to be and this is how it was planned to happen,' " the mom of five continued.

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"Honestly, our relationship was never the same after we started having kids," Spelling shared. "We always said, 'We won't be those parents that change. We'll make sure our relationship is a priority, the two of us. We have date nights.'"

The actress admitted "everything went out the window" once they welcomed their kids.

"And I get it — it doesn't excuse his behavior and everything he did and how he handled things. And I'm not minimizing his part in this and how his lack of sobriety did affect me and the kids for years and years and years," Spelling said.

Adding that she's happy that McDermott is sober, the star said their relationship really changed when she felt like she was alone in parenting their children.

"And he was there, but he was an extra set of hands. He put the car seat in because I didn't know how to do it and things like that.

Emotionally, I was it," Spelling explained. "Like, 'Tag, you're it.' I was the parent."

"And it was a lot of responsibility while also rebuilding a career — which I did. We became a family brand. I went from Hollywood rich girl to cool mom. 'Look at her. She does it all.' Meanwhile, behind the scenes, it was all falling apart."

Last week, Spelling filed for divorce from McDermott, 57, citing irreconcilable differences as the reason behind their split. In court documents obtained by PEOPLE, the mom of five is of their children.

At the time, representatives for both Spelling and McDermott did not immediately respond to PEOPLE's request for comment.