When having a convo like this...don't assuming she doesn't get it, or that she's not listening. I used to get sooooo frustrated when my H would clam up...becaue you really don't know if the other person is listening or tuning you out. But you know what, I've learned...my H was listening, he just really didn't know what to say back.....so he said NOTHING.
This is exactly why I suggested you write yourself out a bullet point list of things you want to say. If you catch yourself rambling, or trying to over explain....it will get you back on course.
Letters are also a great approach, but I think you already said something pretty important. You've taken that approach before, she's not responded to it. So while normally I would say try that...you BTDT, why do what doesn't work again. Try something you haven't tried.
Remember the definition of insantity....."doing the same thing over and over again and expecting different results."
You already know you need to get past your conflict avoidance too right? Try to look at this as a challenge for yourself as well.
I'm not trying to tell you what to do here...just pointing out that you are considering doing something AGAIN, that hasn't worked in the past As you said...
( Then again, when I’ve written her letters in the past, she’s never commented on what I said or made any visible reaction. I’ve waited for days before finally asking her if she even read them. I know I told you this before. I asked if she read the letter, and when she said she had, I asked if she had any response. Her answer was, “I didn’t think it called for a response.")
As you said...