When someone pushing me to accept her apology

Everybody made mistakes..and i also admit that I have made mistakes. I'm not kind hearted person but I used to be someone who can simply forget what bad things people have had done to me.. no grudge..but when my not so called "kind hearted" reach the boiling point, I can get really hurt.. Hurt until I could also lost my control which is quite bad I think...At this stage, it is a bit difficult for me to just let go with what has happened because it has already reached at certain level which my hard heart cannot be melted anymore...