I think she may feel guilt about this and is trying to reconnect (badly, epic fail). She is the older one who did wrong: she has to keep her composure and be humble.
As far as rape-child and keeping him: The minute she decided to keep him is the minute she had to decide to get unbroken and be kind to the child. If you can't, give him up. No sympathy if you turn into a monster. And quite frankly, what she did to her kid is worse than what the rapist did to her. Letting your son get gangraped makes you a monster 100 x worse than the rapist.
There are raped women who love their children of rape. Some give them up. No one forced her to keep the child. She made that decision. Bad decision. It's on her.
I do feel the same, I think she come to repair things she broke but momo's behavior made her angry and said things she should have not and runied everything one more time.
The thing is we still do not know if it was her decision to give birth, maybe it wasn't and she was have to, plus pregnancy is alone something hard and many women has depression after birth, sometimes they just can not love their kids without even something like rape tho. I'm not saying she is not at fault what she did to momo is unforgivable, letting a child (forget about the fact he is her child) get gangraped is unforgivable. I know and I'm not try to say it is. But seems like she was not mentally ready to have a child. Again I'm not try to say it's not her fault bc it's but there is two sides.
I don't have a sympathy for the mother but I can understand why she didn't love him or she didn't project him. Giving birth to your rapist's child probably destroyed her. Everytime she looked his face, she probably saw some similarities with them. She even could want to Momo suffer like her, taste how it feels like to someone touching you against your will, she even could thought of her getting revenge from her rapist like that. Again I don't have a sympathy for her, she's a bad mother for sure but before she is a mother, she is a human and she is a broken one.. I think it wasn't like she didn't love/project him, she just could not.
For Momo I don't even have word anymore, the moment he start to feel happy, loved and even made a friend, his mother show up and ruined everything. But I hope this will make him even stronger and won't be suffer anymore than this. I want to believe he will be fine because someone like Yata is next to him.