Seeing the two of you so distressed was hurting Elizabeth even more than your desire to be a man again.
After a long hesitation, she finally decided to sit with you two, placing herself on the other side of Selene. She tried to help you, tried to help calming down Selene, her new head-sister. At this moment for Elizabeth, the only significant thing was that you were both sisters trying to comfort their head-sister. That you too, were a sister that needed to be comforted.
Somehow, you were able to feel Elizabeth love and support, and were grateful for it. You were still viewing you as 'Michael, the man unjustly turned siren'. But, as the same time, you now also fully accepted Elizabeth as your sister, as what a siren call a sister.
The way you were thinking of your wife was similarly affected. You still loved her as much as ever, still loved and respected her as any husband should love and respect his wife. But at the same time, you were also loving and respecting her as most siren love and respect their head-sister. The one that can make decision affecting all your sisterhood, the one to have the final word if conflict arise between sisters.
Even how you were seeing your unborn daughter was similarly affected.
Your wife felt you acknowledged her as your head-sister, your acceptance of the sisterhood. At first, it only increased her panic, but as soon as she looked at you, Selene too accepted to see you as both her husband and sister simultaneously.
The tree of you unknowingly discovered an alternative way to revert your transformation. Some might think of it as a sort of cheat-code.
Your willfulness to get your manhood combined with your acceptance of the sisterhood made you change back. And more your sisters fully accepted you, the faster you returned to being a man.
Sensing Selene's change of mood, Elizabeth and you finally became aware of the change.
To your surprise, when you were fully a man again, Elizabeth enthusiastically hugged you, shedding tears of joy while shooting "WE STILL ARE SISTERS! WE STILL ARE SISTERS!" And in a way it was true, since reverting back to being human didn't break your link with the sisterhood, you all sensed it.
Your wife also sensed she wouldn't need any other food than your love, and neither would your daughter.
Elizabeth, however, still needed to hunt men and eat their life-force. But as her sister, you couldn't blame her for it.