What is the ruling on visiting a secular father who abuses the mother and children, and from whom manipulation is feared, knowing the obligation of honoring one's parents?

If the father is an infidel and has apostatized from the religion, then his marital relationship with your mother is not permissible, due to the Almighty's saying: "And do not marry polytheists until they believe" and "They are not lawful [wives] for them, nor are they lawful [husbands] for them." As for you, as children, you must treat him with gentleness and kindness within the bounds of Islamic law, and strive to advise him and invite him to the truth, while supplicating for his guidance.