1. We don't know if Meru would have been allowed to "go back". Correct me if I'm wrong but as I recall she was taken against her will from the caves or whatever along with a bunch of other women and at no point during the taking was anyone allowed to say, "no thank you" and left alone. If she could have after a month of Dukat's bed said she wanted to go home do you really think she would be allowed to? Sure he may have cast her out of his bed, sure he may well have not killed her, but that's no guarantee she would go home. More likely shipped off to some Cardassian workhouse, maybe even on trumped up charges that kept her in a penal system. There's your paperwork taken care of. Nothing about Dukat indicates that he would let her go home just like that.
2. I agree she drank the Kool Aid. However:
Kira has very black and white thinking and her character arc is often about learning to see that life is more complicated than that even, or especially, during war.
Her mother was ultimately a survivor using whatever tools she had for taking care of her family which included taking care of herself. If she had let her position as Dukat's sex slave psychologically and emotionally destroy her he would have lost interest in her and discarded her. Her children would no longer be fed. So by embracing the role and enjoying aspects of it (good food, physical safety, conversation) she kept this arrangement, and therefore her children, alive. This is not weakness.
If she was constantly telling her self that? Like Walt on Breaking Bad... "I'm doing this for my Family" Fine.
But Meru drank the cool aide.
There was no moral scales, no constant assessment of if she had gone one hummer too far. She sold out her planet for fresh fruit.
She could put aside all her fears and concerns for her children getting food (and that's what Nerys says, that she remembers eating better).
Both of these things can exist simultaneously, that she was seduced by luxury and Dukat's charisma and
that she had peace that her children were being cared for and spared being rounded up and sent somewhere more heinous than their current life (like a laboratory or a particularly awful camp). However much she was personally seduced, that her children's wellbeing was no longer something she feared for cannot be left out of the equation.
Meru never once considered saying no, or sticking a knife in Dukat's throat.
Would she have stabbed Dukat or tried to leave if she didn't have the assurance and the peace of mind that her children were fine? We do not know. Not everyone can be a hero, but that doesn't make everyone who isn't is a coward. We do know though that for Meru the stakes were considerably less high once her children were safe.