General Opposites:
* Kind
* Compassionate
* Merciful
* Gentle
* Caring
* Benevolent
* Humane
* Tender
More Specific Opposites:
* Forgiving (opposite of vengeful)
* Sympathetic (opposite of unfeeling)
* Understanding (opposite of unsympathetic)
* Nurturing (opposite of abusive)
* Protective (opposite of exploitative)
* Supportive (opposite of indifferent)
The best word to use will depend on the context of the sentence.