Originally the Forgotten Realm shared a cosmology with other D&D settings, which was The Great Wheel cosmology. But with 3rd edition it separated and the Great Tree cosmology was created. In the Great Tree there was a plane called "Barrens of Doom and Despair". Sometime after that in 4th edition the Spellplague took place and the World Axis cosmology was born.
My question is this: What happened to the Barrens of Doom and Despair? Was it merged with some other plane, was it totally destroyed, or does it still exist somewhere in The Elemental Chaos?
I'm asking because I have characters there (demigods) and until now I was ignoring the Spellplague (mostly because of unfamiliarity). Lately I decided that it would be fun to move forward, but I don't know what would happen to someone who was in Barrens during the Spellplague. Of course these demigods are not mere humans and so are not easy killed.
I was researching this topic in the books Manual of the Planes for 3th and 4th edition, but with no luck.