Sandra Mihanovich has been a very popular Argentine singer since the early 1980's, and when "I Am What I Am" was still a new song (1984) she recorded her part dance version, to some acclaim in that country, and she's still singing it. I found videos of her doing the song, in Spanish, "Soy Lo Que Soy," one being a studio track, and many other live performances.
While it's always iffy research when googling foreign language websites, I gather that Mihanovich has not been all that publicly out of the closet. Her one-time partner, Celeste Carballo on the other hand, has been very open about being lesbian. In a 2004 interview in the UK magazine Diva, it was indicated that "Everybody knows that Sandra is a dyke. But, people say, she doesn't make a song and dance about it the way Cece does"
I found a video of Sandra and Celeste performing together, in 1988, and the album cover below, from 1990, is a bit more explicit.
After I posted this blog entry an email correspondent of mine in Argentina wrote me that Sandra's mother was a TV celebrity there and it was she who would not allow Sandra to come out publicly. But Sandra did appear for the first time in the Gay Pride Parade last year. The way my friend described the coming out was that despite her mother "you cannot hide the sun with a finger. And 'soy lo que soy' was a sun for many of us...the first gay hit (sung by a lesbian) ever in Argentina after the dictatorship."