It sounds like you're doing really well. Finding that balance is really hard and it takes noticing when you didn't quite hit the mark and trying trying trying more.
I had a book that helped me a lot, Family Communication by Sven Wahlroos. It helps you to see that when you're dissatisfied and you express it by getting quiet and polite, you're hurting your relationship. It also helps you to see that sometimes it's you who's in the wrong. When you're the victim so much it can seem like you're the only victim. In your story about talking about S's surgery and you wanted to change the topic to you, and he ignored you by continuing to talk about the surgery, you felt mad because he was ignoring you, but you also had ignored him. He was trying to say something too. I know you know that now, but I'm restating it to show the point clearly.
You learn to hold the things you want to bring up until it's the right time for them to be heard, not simply the time they popped into your head or nagged at you. Communicate with intention.
Spending time as a family around your son's recovery can be a good chance for you to try not to be resentful if you can manage it. He can begin to see that it's possible to come back. There would be time later to work through resentment if he's willing.
I'll be thinking of you!
Adinva 51, S20, S18 M24 total 6/15/11-12/1/12 From IDLY to H moving out 9/15/15-3/7/17 From negotiating SA to final D at age 50 5/8/17-now: New relationship with an old friend __ Happiness is a warm puppy.