Chabakuk Elisha commenting on Tomer Devorah & Babka.com:
I know that this is a theme often touched on in Chassidus, Mussar and other sources, but it is a tricky thing. It can make someone easy prey, and reward bullies if not applied properly; that's why I was pleased to notice that you say the person has been helpful.
There are some who misinterpret remarks of this type, thinking that they are meant to display kindness to those who harm them. We must remember:
1. One who displays favor, forgiveness or kindness to evil people, ends up harming innocent people.
2. Turning the other cheek is not a Torah concept.
Forgiveness is without question a Torah ideal, and should be used whenever appropriate, but as my father always says, "You’re not obligated to forgive people who aren't even sorry for what they did." (Obviously, it's also important not to get yourself down, and we don't believe in revenge.)