How comes your dark urge and tav exist in the same universe? It's canon he killed them in a comic pre game
Fair assessment, I also read/played that lil' snippet about Tav's fate.
But much like Larian goes "ay if you pick Tav then Durge just dies" in a wacky woohoo kinda way, I too did the same and just said "nah, both"
For an in Lore explanation it's also quite simple; Nimue never went to Baldur's Gate, ever, or rather never reached her destination. She's from the High Forest, spent most of her 200 years there and eventually wandered into the Frontier's direction when she sought for a change and more knowledge. On the way there, the Mindflayer abduction happens.
So basically, Nimue never set foot into Baldur's Gate nor was close enough at any time to the Bhaalspawn pre lobotomy to have been killed by him.
And now they all smooch, the end 💖