Hi I don't think you should give such a letter to your W. Think how you would feel if you recieved something similar. I'm not saying you shouldn't write anything but you need to tone it way, way down. Are you trying to improve things or just to lash out in defense at her extreme reaction to your comment. She has been trying to make things better. I agree you need to talk throwing a plate of food is pretty childish!! But remember better communication is not about being brutally honest. If you are so aggressive she will just take it all as an attack and get defensive.
I don't know if this is very good advice but what I would do in your position is to apologise, give flowers ect. Say you realise how much she has done to try and improve things but that you are still having some problems. You want her to try and address those remaining issues with you and that you know that together you can make it work. And you want to make it work because you really, really love her ect.
I am always one for a positive approach. Be as positive as you can in the circumstances.
