Different Drummer: Welcome. First, may I say you are extremely well "spoken" (expressed?), I'm thinking you write for a living?
Anyway, I could have written exactly what you have (ok, well, not as well!) a few short years ago.
I will quote a person who told me about myself, who, at the time, I had never met before. She helped me get on the fast track to healing:
She said (essentially):
"you are a person who would never hurt anyone. As a result of possibly lifetimes of almost religious level care of others, you have lost your seniority over your own life. You think for a long time about a decision, ruminating out all the possible consequences, and then make a choice. But if anyone comes along and questions that choice....because you can see "all sides" of things, and are able to actually feel what others are feeling, you say........'oh, maybe that's not such a good choice I made' and you give up your power".
Sound familiar? Granted, there are a million variations and other contributing factors (my parents were not N, but I sure had enough of them in my life), but as I read your post, it reminded me sooo much of that conversation.
Lots of people on this board, I think, have this ability to heal and feel for others, and that is WHY N's use us so easily....and perhaps why we chose N's to have relationships in this lifetime (and to go out on a limb, I'm starting to feel we are paired with parents as well, as a spiritual choice, so that we learn what we need to as a soul.....but that's a far out there discussion for another time, I suppose).
As soon as I figure something out, the universe sends in a "test" so I can practice, whether I want to or not. Sounds like your first (or maybe hundredth) test is coming up.
I echo what Daylily and Selkie have said: keep it simple. You can ONLY have control over yourself. I know that even as a teacher, the most compassionate thing I can do for my students is to set boundaries..for myself. For example: "I am going to help another student. When you can ask me for help in a more controlled/respectful/insert behavoir here.....I would be happy to listen and see what I can do."
or as a parent: " I feel upset. I need a little time alone. When we are both calm, I will discuss this with you".
OK, just so you know, I am not always soooo level headed. I'm human.
But I know this stuff works...WHY? Because I am working from my intention, and I am being honest. The only thing I can control is myself. I am still respecting the dignity of the other person, without giving up my own power. I am leaving them with their power, and I am simply stating some compassionate boundaries. We call these "I" messages for the younger students... and it's part of a lot of conflict resolution programs in schools.
Sure, I know your folks have history with you in the way the "dance" has gone before....but step out of it. Decide what YOU will do, and don't even concern yourself with, or practice, or envision what they will say or do, as you will give THAT energy, and the new script for your life is YOU ARE IN CONTROL OF YOU. The only "practice" you want to bother with is the one that repeats your own good intention and power to yourself, as daylily suggested.
You seem to have a wonderfully supportive husband and I have no doubt you can weather the storm of changing this relationship with your parents together.
As I said to a student recently, who was upset that another kid "stole" his place in a waiting line...."if you don't care, it can't hurt you"....so he told me and the other kid he didn't care, smiled, and boy the kid who stole his spot was pissed! You see, the "victimized" kid changed the dance!
So should you not care about your parents? Of course you should, but you can choose NOT to care if they: make faces, judgemental comments, try to get you to change back, etc.
Send them love.....just not your power. You get to keep that.