JOHNNY GALECKI took a “Big Bang” to his ego after his teen sweetheart Sara Gilbert revealed that she realized she was gay after making out with him!

Now 38 and a co-host on “The Talk,” Sara recently revealed that she knew she was a lesbian after hooking up with Johnny, who played her love interest, David, on “Roseanne,” in the ’90s.

“I thought he was super cute and I had a total crush on him,” Sara recalled of her former co-star. “We started dating and he would come over and we would, like, make out, and then I would start to get depressed.”

Sara says she called Johnny before the Sept. 12 show and claims he was completely supportive of her decision to share her secret.

But a source close to the actor said Johnny really didn’t have a choice.

“What else could he do? He’s not going to say, ‘No, don’t do it!’” said the source. “That would just make him look petty.

“Deep down, I think it must have wounded his pride a bit.”

Sara said that after her romance with Johnny, she went on to date a woman 18 years her senior who was “also in the public eye.”

Sara and Johnny, 38, who’s currently dating “Pan Am” actress Kelli Garner, remain friends. She even makes guest appearances on “The Big Bang Theory.”

As The ENQUIRER previously reported, Sara and longtime partner Ali Adler split in 2011, and the actress is now happily engaged to songwriter Linda Perry.