How is it possible, given your experience, for someone to forgive those who have done horrible things (such as genocide)?
I do not expect people to readily want to forgive those who have done horrible things. Some people say that once such horrible acts occur, then forgiveness is never possible. Yet, there are those who have forgiven people for such atrocities. It is a matter of public record: Corrie Ten Boom in her book, The Hiding Place, is just one example as she forgave Nazis for killing her family members.
I use the term “forgivingly fit” to describe how it is possible for people to forgive where others would never even consider it. As people continually practice forgiveness in the little things of life, they build up an insight and a practice of forgiving that helps them when tragedy strikes. This does not at all mean that those who refuse to forgive in these contexts are bad people, not at all. We all have a choice of forgiving or not and to refuse should not lead to other people condemning them for this.