My 2 cents; How does forgiving someone help? Because when you forgive, you don't hold this inside of you. You can think of it as self defense. When you look at someone whom you believe has committed evil or is toxic you resist them and what they have done. By doing this you weaken yourself, this can be tested with a muscle test. In Aikido we use to do a physical test where someone would be walking towards you and you would be thinking "this is my enemy, this is my enemy" over and over. When they approached and pushed on you, you were very weak and couldn't resist their blows. When you did the same drill only thought "This is my friend, this is my friend coming to help me"
you would remain very strong and it was almost impossible to move you.
The Buddhists have said something similiar to making Evil their teacher. It totally changes their energy make up. They do not fear evil or resist it.
The best is if you can "love" evil. It is the strongest force.
If you try this out, you can see there are very practical applications to Love, Kindness and Forgiveness. You remain strong even in the face of danger.
Forgiving Evil can protect and keep you strong, do it for yourself not for them. Love yourself, Be Kind to yourself and Forgive yourself. This has many ripple effects and others pick up on it if you do.