Am I sinful if I cut off contact with someone who verbally abused me several times, while maintaining a peaceful demeanor, and refused to reconcile with her to preserve my dignity?

The Sharia (definition) has forbidden a Muslim from abandoning his brother for more than three nights, and the better of two who have abandoned each other is the one who initiates the greeting. If a woman wrongs you unjustly, it is permissible to abandon her for only three days, and the abandonment ceases as soon as she greets you. Forgiving the one who wrongs you is among the best deeds and raises one's ranks, as Allah Almighty says: "And let them pardon and overlook. Would you not like that Allah should forgive you? And Allah is Forgiving and Merciful." And the Prophet, peace and blessings be upon him, said: "Allah does not increase a servant who pardons except in honor." However, if maintaining a relationship with her causes harm to your religion or your worldly life, then it is permissible to abandon her, for Ibn Abd al-Barr said: "And perhaps a beautiful severance is better than a harmful association."