I have a friend whose father left her when she was very young.
She hated her father so much that she did not even want to pay for
his funeral but eventually she still arranged for his funeral
reluctantly. She only learned to let go her hatred when she
became a Buddhist and knew about karma.
Her method of letting go is very effective. She told me whatever
she owed her father, she had already paid. She did not wish his
father to pay whatever he had owed her because she did not wish to
be reborn again. She said she had forgiven her father as she did
not wish to entangle in this karma debt. 怨怨相报,何时了!
I personally find that I can forgive but cannot forget. I was
once a very revengeful person but I'm a better person now after
becoming Buddhist. Sometimes I feel better when I think this way,
everyone has to answer to his bad deeds 因果自负。
Yes, I most surely do not want to be reborn just because of an
animosity I could not let go off. Most of the time I try to
let go. In the midst of the problem, it may be hard to let go
because that person may still be harming you. But later, with
time and a different perspective, letting go is possible.
I have managed to forgive. It's not impossible. I've
found that when you can see from the other person's perspective,
even if their actions were harmful, it is that bit easier to let
go.
Lately also, I've been thinking that problems persist sometimes
also because we did not have the wisdom to defuse the
situation. In retrospect, we can often see how we
participated in perpetuating certain difficult situations (like my
problems with an aunt). Not always easy, but oh well,
learning process bah!