Gerda, I am so sorry you have to go through this. Those letters are very cold and selfish and the wording is just bizarre, not even taking in to account the content. Who talks like that?
I know how you feel about how the conversations break you down. I have always been a very confident person, but this thing has broken me down. Me and W had a great relationship before so I don't even get a real excuse as to why this happened to us. I cooked, cleaned, did laundry, helped with all the kid stuff, took care of the cars, and the yard duties. I also have a good job and not to toot my own horn...but am told that I'm a looker too. Not to say I did all that stuff on my own without her, but we shared all the responsibilities. Her only complaint is that we lost out connection to each other and didn't go out enough as a couple. That may be true as we have 2 teenage kids with full schedules, but it was something that I wanted too and tried to work on once I realized it was an issue.
My point in telling you that is to say that they will find an issue to justify their "feelings" even if there isn't one readily available. Please try not to take the things he says personal. Sure there may be a kernel of truth to what he says, but this is not how couples handle these things. I've owned up to my part, and it sounds like you have too...but it hasn't been enough to turn things around. That's because it isn't really about us. Its all about them and the demons they have to wrestle.
In the end, they just have to work through it themselves and we need to protect ourselves in the interim. I wish that were as easy to do as it is to say. I struggle often. Try to put the focus back on you and do something that makes you happy and I'll do the same.