Sean Weber-Small, Billy Joel's former stepson, is opening up about his complicated relationship with the singer for the first time in the upcoming documentary "Billy Joel: And So It Goes."

Weber-Small, 58, told PEOPLE that he and his mother, Elizabeth Weber, had been silent about their time with Joel since 1983, and that talking about it would "cheapen" the memories.

Joel and Weber's marriage dissolved, and Weber-Small's relationship with his stepfather became "more complicated." He described Joel as a "bit of a conspiratorial uncle" who was clear that he had a dad, but also had authority over him as a child.

Weber-Small said that he and Joel would see each other if they were in close proximity, and they kept in touch through phone calls and emails. He described their communication as "nice" and said that it was "healing" to revisit their early memories through the documentary.

"Even a lot of the people that are here tonight, seeing everybody, there's shared universality in our experiences that a lot of us didn't realize until now," Weber-Small said.

He added that he's excited that his mother is finally getting her due, and that people will get to hear their story through the documentary.

"My mom didn't get her due for a long time and kept her mouth shut, and kind of, in my opinion, took the high road. So people are going to get to hear her story and our story. And I think that's really exciting," he said.

Billy Joel: And So It Goes is set to hit HBO in July.

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