All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad is His slave and Messenger.
If your parents are separated, then there is no impediment that you stay with your mother if you are safe while staying with her. Please refer to fatwa 308878.
In any case, you must be kind and dutiful to your parents, and it is not permissible for you to desert either of them.
Allah knows best.