Sounds like you are hell bent on revenge. The thing about revenge is that there is no satisfaction in getting it unless you are there to see it happen. As it is, you will write a spiteful letter which you will never see opened, and yes, the hurt and upset you cause at that time will be devastating, but you won't be there to witness it. Instead, after writing such a letter, you will think about it all day, every day, imagining the effect it will have. This will eat away at YOU and I imagine you will become more bitter and upset the longer it goes on. So, you have two options. You either shut up and live with it (as you have for so long) or you confront him, probably have an almighty row, but at least clear the air as far as you are concerned. Chances are, being a man, he has absolutely no idea of your festering resentment and the whole thing will be a shock and surprise, because he thought it had been dealt with and gone away. Then you can both deal with it (once again, in his view), make up and move on. I wish you both well and hope you can resolve this together.