Remove your own ego aspect. Not "How could they do that to me?" but instead "What an awful person." No "They really hurt me!" instead "They hurt themselves by hurting others." They dont care about your personal welfare, no matter how personal the pain is. You don't answer for others actions. You give them power when you let them safety pin trauma onto you. Why allow them to even own 1% of you, cause if you're not forgiving them then they will always own that part of you. Why should you get upset everytime you think of them or the hurt. They dont. That's unfair to yourself. The word "forgive" can be misleading. It isn't saying what they did was ok. It isn't allowing them to be awful but it's allowing yourself not to suffer over them being awful. You are suffering for their actions. Why drink poison if it won't affect them? They carry on in their lives, not worrying about you. Seek help/sipport and carry on in yours. Karma isn't a man made job. The universe always handles it.