Was hoping she didn't knew what's right and wrong, but she clearly knew what she done was bad, put her mother through persecutions along with divorce.
She is clearly insane and knows about it or too fucked up to realise anyway.
Just put her out of it, it's the best for the world if she doesn't realise she's hurting people whoever makes contact with her or Ichinose.
If we should suddenly feel for her, you have to be really fucked in the head to root for her.
Just end her, serve some time in the jail, which would be probably not too severe for what she got him through and be glad in heart you made the world better by getting rid of a stain on the world she is.