I think it takes a lot of courage to do what you are doing. I also think it can be very helpful to you in moving through the process and dealing with your feelings.
I was able to say those things to Z, albeit in a phone call, the day I told him I no longer wished to reconcile. As someone who has already done this, I would like to offer you a few observations from my own experience.
First, telling Z that I was not angry with him but that I was letting him go and the finality that that brought to me triggered some sadness that I had not anticipated. Not that this is a bad thing, just something to keep in mind.
Also, be careful not to have any expectations at all. This was easy for me to avoid because the conversation was very spontaneous, he called because I emailed about getting him to release my cell phone and the conversation just evolved, so I did not have the time to develop any expectations. Not to say you will, just a friendly warning.
Third, one can feel pretty empty when the conversation is finished, so having a friend to talk to once you are ready might not be a bad idea. A good friend was there for me right after the conversation and it really helped me a lot.
You obviously continue to move forward and through your process, not avoiding anything. Just keep doing that and everything will fall into place, in time.
