"He hasn't expressed any needs yet. He still claims he was perfectly happy with the way our M has been."
I know it doesn't make it feel better, but I want you to know that this is pretty typical. When my husband wanted space and left, I went almost into a denial, as I think most spouses do. While your spouse is often making the marriage out to be worse than it was and rewriting history, you are often making the marriage out to be better than it was, and also rewriting history. So, I know that doesn't fix it, but I want you to know from what I've seen here, it is a normal behavior and process and it takes time for the other spouse to get over the shock, to really wake up and then start to look at what was wrong. They will often then see what the other person did wrong, but eventually will start really seeing what they did wrong, and then seeing as well how their needs weren't met in the marriage and what those needs are. It is a process..... one day at a time and don't make yourself make any decisions too quickly. Right now the emotions are raw on both ends and it is best if you can find a way to limit the conversations and interactions if they are going to lead to you saying anything you know might impact you both longer term or causes you to feel even further pushed away. Things that were fixable, can quickly get dug into a hole that seems hard to get out of, so really give yourself some space right now to make clear decisions and to pick your words and emotions carefully when interacting with your H.
Very little is needed to make a happy life; it is all within yourself, in your way of thinking. -Marcus Aurelius