People who are nasty towards us deserve even more of our sympathy.
Ultimately, whether a person is kind or unkind, good or evil, they are still a child of God, and their inheritance is Heaven. God loves every soul on earth immensely (no matter how good or bad they are) and so He suffers deeply every time a soul chooses darkness over Him. If we love God, we should desire a person’s salvation and sainthood, as much as God desires it.
So no, everyone deserves our sympathy, empathy, kindness and forgiveness, no matter how much they hurt us. In fact, it would be a sin to be hurtful, unsympathetic or unforgiving towards any person, no matter what they have done to us, because that person is still a Child of God. Obviously, the Church doesn’t encourage a person to remain in toxic or harmful relationships (for example, domestic violence, bullying, etc) but we are called to pray for the people that have wronged us - pray that they will be forgiven for their wrongdoings, be freed from sin and obtain Heaven when they die.
Some of the greatest Saints were sanctified by means of praying for and loving the people that hurt them. There are many, many examples of such Saints, but the greatest example is Jesus Himself. He prayed for His persecutors: “Father, forgive them, for they know not what they do.” Even though they were torturing Him, humiliating Him and killing Him, He loved them so much and longed for them to obtain Eternal Salvation one day.
It’s not easy, and it takes a lot of humility and compassion, but we are called to do the same.