I have to hand it to you, here. The level of RP you are talking about is incredible. For Aranwen to go from disciplined Bladesinger to brainwashed cultist and would-be mother of abominations.... just, whoa.
I get how that could happen, of course. Like you said, her mind would be broken.
But still, it takes some kind of special player to even admit that kind of thing could be a possibility.
Course, I have to point out... if you go back another silver screen moment, you see that syls don't fare well in that role. That doesn't mean that the cult might not try...