Is the questioner considered sinful and a severer of kinship ties for not visiting his paternal uncles and aunts who caused severe injustice to his father and deprived the questioner and his siblings of their rights, due to his lack of love for them and his feeling of pain and sadness upon seeing them, despite his knowledge of the virtue of maintaining kinship ties and his fear of Allah?

The characteristic of a free Muslim is eagerness to maintain communication with their relatives and patience with their harm. Whoever endures their harm and repels it with goodness, Allah will protect them from their evil, preserve them from their plotting, and grant them His divine support. In a Hadith from Muslim: "If what you said is true, then it is as if you are feeding them hot ashes, and you will continue to have support from Allah against them as long as you persist in that."

Supplicating against them is permissible, provided you do not transgress, meaning you do not exceed in your supplication against them beyond the extent of their injustice to you and your family. However, if your grandfather is among those you supplicated against, then it is not permissible at that point; rather, your supplication against him constitutes disobedience (to parents/elders), from which you must repent, for dutifulness to one's grandfather is obligatory, just like to one's father.

Regarding maintaining ties with them if you fear for yourself and wish to avoid their problems: it suffices for you to contact them by phone, inquire about them, and greet them, and there is no blame upon you after that. Maintaining kinship ties has degrees, some better than others, and the lowest degree is to avoid abandoning them and to maintain ties with words, even just a greeting. This varies according to ability and need; some are obligatory and some are recommended.

In matters of disputes and litigations, one should refer to the Sharia courts and judiciary for resolution. However, it is preferable for relatives to resolve their disputes through reconciliation.