That actually happened?
In a Supergirl comic I believe, but yes. I think "Pink-K" was only used the one-time though to... prove some kind of point? I don't know. But, oy!
Somethings are best left gone by the New 52!
First established in superman 72 in 1953.
Are you talking about Kryptonite? I believe it started earlier than that as a plot-device in the radio serial and first appeared not long after that.