Really sorry to hear this, I know how frustrating and painful that must be. From what you shared, you reacted the way most of us would have, and it’s awful to see that it still wasn’t enough.
Given the bloom, it’s likely a good amount of food was still left behind, leading to a rapid oxygen drop which likely caused the losses.
You’ve already gotten solid advice here, and separating the CUC was a smart move. I’d also suggest adding aeration if you haven’t already, it’ll help both oxygenation and ammonia breakdown. Running carbon can also help pull out any excess organics.
Once you have current water parameters, we can figure out the next steps and get things moving in the right direction.