Not VX, but don't you remember this as well: https://en.wikipedia.org/wiki/Tokyo_subway_sarin_attack

I actually ended up in the same article because VX is related to オウム真理教(Aum Shinrikyo), the group that was responsible for the gas attacks in Tokyo. They were also manufacturing VX and are the only ones on record to have used it to commit a murder, until now I guess... https://en.wikipedia.org/wiki/Aum_Shinrikyo

To be fair, the form as it existed in that movie sort of was... although not by much.

I'm in exactly the same boat as you and thought VX was fictional until about 10 years later when a mainstream media article made a reference to it.