EDIT: No problem, DZ. I like everything you have there except for the first couple of lines. I think it’s a cool real-world moment of having a cult preying on desperate people. It also allows the sentences to flow better into each other:
“Sith cults prey on desperate people like them… Your barren mother, so desperate for a child.”
Perhaps they gave promises that she would be able to become pregnant if she joined them - which never came to fruition. Which is why she takes Rey, both to get back at them but also to have her own child. I think it’s more effective characterization than simply having second thoughts after joining a cult.