Sara Gilbert realized she was gay while dating Johnny Galecki

"The Talk" this week has been about sharing the co-hosts' quietly kept secrets, and Sara Gilbert opened up with one involving a former "Roseanne" co-star.

When Gilbert, now 38, was starring on Roseanne Barr's '90s comedy as Darlene Connor, she was also dating her co-star Johnny Galecki, who happened to play her on-screen love interest, David.

But that's not the secret (as Gilbert says, some "Roseanne" fans probably already knew that). Here's what she spilled:

"I thought he was super-cute and had a total crush on him and we started dating (as teens)," Gilbert recalled. "And he would come over and we would like, make out, and then I would start to get depressed."

Becoming emotional, Gilbert explained that Galecki began to feel badly about her reaction and was taking it personally, "so I eventually told him that I thought it was about my sexuality, and he was super-sweet about it."

When Gilbert began to date a woman 18 years her senior while doing "Roseanne," Galecki helped her keep the relationship under wraps.

"(She) was also in the public eye, it was something people really could've found out about," Gilbert said. "No one knew at the show for years, and Johnny held the secret the whole time. And I just felt ... always so scared if it came out, what could happen. Would I lose my career, would I ever be able to play a straight role again?"

Gilbert did eventually come out, and confirmed in 2010 at the start of "The Talk" that she's a lesbian. But even though she loves her life - which includes two kids and fiancé Linda Perry - she does still have some of that same fear.

"When I talk about my sexuality on the show, or in public, I still feel really scared. ... There's still a piece of me that goes, what is this costing me in my career?" Gilbert said. "I want people to know that we often say things like, 'It gets better,' and it does get better, but I want people to know that, I guess, that there can still be a struggle with it and that's OK. It really is a process, and there can be a part of you that doesn't want to feel different or feel scared."

Thankfully, Gilbert has friends like "Big Bang Theory" star Galecki to support her. The actress said she called Galecki prior to sharing her secret to make sure he was OK with it, and he gave her his blessing.

"He said, 'I love you and I think it's really important and I'm so proud of you," Gilbert said, adding that he even offered to come on the show with her and hold her hand.