From my experience the past few years, the loss of relationships and the grief associated with the loss has been the most difficult. I'm not sure it matters what role the person is in to us, or whether the loss is voluntary or involuntary (I primarily mean death as involuntary). I don't share the perspective that a voluntary breakup, or a person choosing to leave, means that you have to view the past differently than the day before the breakup. The relationship is the relationship before it ended, and the ending doesn't rewrite the rest of it, IMO. I also don't think that what one person does means that everybody will always do this or people always do this. Figuring out how to manage the end of a relationship without making the other person into something evil and keeping myself together has been something helpful to me. Although I don't always get the ending that I want, working towards having a better ending, one that honors the relationship and what it has meant to me, has made me feel better and stronger.

You still have some time to work on the ending, and I'd encourage you to do so, whether you want to say to him some of what you have said here, or just grieve, or find a way to move forward that benefits you and your life. You know best about what is useful for you, i'm just making a suggestion.