It can be quite difficult to forgive especially as we can never forget. But if we can't forgive we are holding a burden within our mind that only we think and feel of that will weigh heavily and take the edge off of everything that life has to offer. Many people can't forgive or don't want to as they feel it is a justification for themselves of the past whereas it's nothing of the kind. Such selfish thoughts lead nowhere but to a state of depression and a life full of lack.