I have felt like you do before. The heartache lasts longer when it was one of those things where you still love him, but just know that the timing isn't right. Its easy to think it would be easier to get over him if you caught him in bed with your best mate. Then at least the anger would distract you from the pain.
But know this, if its ending on relatively good terms, then you must have picked a good bloke, who hasn't resorted to name calling etc at the end of a relationship. But do remember also that he isn't right for you or it wouldn't be ending.
I have has 3 four year relationships and each of them was very special to me. They all worked for that particular moment in my life. But I am a different person to what I was 10 years ago. The older I get, the more I know myself and what I want and need in a partner.
If you think that some friends are great for some things only. For example, I have friends who are great for going out with and giggling about men, some who are great to invite round for some cake and a natter and some who know all about my job and will let me moan away about it and totally get what I am saying. I have a few very good friends who can be all of those people and know when is the right time to be each of those roles.
In relationships I think that there are a lot of men who could fulfil one part of what you need and there are less who could fufil all of them. But there isn't only ONE person who could do that, but they are certainly a rare breed.
I know its hard, but try to be happy that this has finished without resorting to hatred. Learn from what it has taught you and go into your new single world knowing that there are others out there who will suit you perfectly and take you in new directions you didn't even know about.