I did read, but seems like you don't grasp what you say yourself... Free us all, which means HERSELF... otherwise it would be FREE YOU all.
What deal could she have with the death god to escape torment? Oh, dunno, maybe killing plenty of people to feed the hungering maw.
So how are those people she kill FREE when they are being fed to the jailors torment which supposedly is what Sylvanas tries to escape?
Nothing of this is freeing anyone from anything.
If she just wanted to free everyone from living and don't care about the rest then why did she leave Bolvar alive?