Oh hon

No idea on what to do with sleepless toddlers, but could you try industrial headphone or earplugs? As they work on attenuating a general frequency range as well as more of the nastier higher frequencies they might at least help you tolerate the screaming if you are not in physical pain from it.

I know that this is only the tip of the iceberg in terms of what your dealing with, but if you can at least make one part of it easier to deal with, then it might have a flow on effect.

Good luck sweet.