"It's a situation that I consider private. This is a very personal journey that became very public," Pinkett Smith said on Friday's episode of her Red Table Talk series.
"Four and a half years ago... I started a friendship with August and we actually became really, really good friends," she said, telling Smith -- and viewers -- her romance with Alsina took place during a difficult time in their marriage.
"I was done with you," Smith said.
"We broke up," Pinkett Smith said. "We decided that we were going to separate for a period of time. ... From there, as time went on, I got into a different kind of entanglement with August."
Pinkett Smith shot down reports claiming Smith gave Alsina his blessing to date his estranged wife.
"The only person that can give permission in that particular circumstance is myself," she said, explaining Alsina eventually broke off the relationship and she and Smith worked things out.
"We came together young, and we were both broken in our own ways and to be able to make mistakes without the fear of losing your family is so critical," Smith said.
"Yeah, it's the idea of any relationship in trying to get to deeper understanding of love is going to be forged in fire," Pinkett Smith said.
The couple married in 1997 and have two children together.