What is the ruling on avoiding communication with one's father and minimizing time spent with him due to his past ill-treatment and discrimination among siblings, which causes psychological distress when interacting with him?

All praise is due to Allah, and may peace and blessings be upon the Messenger of Allah, his family, and his companions. To proceed:

If your sitting with your father leads to harm, there is no sin in reducing it in a way that repels the harm. However, honoring one's parent is among the greatest acts of obedience, so do not let his ill-treatment of you in childhood prevent you from honoring him. Seek Allah's pleasure through honoring him, avoid displeasing him, and treat him kindly as much as you can. For the reward of honoring parents is immense, as stated in the texts.

And Allah knows best.