So Hulda dies. I had to finish her off since she sent 3 thugs after me. But anyway she is dead, and in my skyrim playthrough rules, dead npc = dead, no load older save.

However UESP and elderscrolls wikia states that ysolda will take over hulda if hulda dies. BUT, why didnt ysolda take over? She is still found roaming around whiterun talking about her merchandise and i did complete her quest.

Did i fk the game up?

The USKP corrects the backup alias to Mikael the bard, who actually has the proper dialogue to advance "The Whispering Door"; Ysolda backs up Belethor as intended, instead.