FF, I really feel for you and I understand why you don't want to take the kids away from the house and why you don't want to change jobs. Those aren't trivial matters by any means. Separating would be hard enough and stressful enough without adding to it trying to get settled and make friends for your kids in a new neighborhood, and starting a new career. And if you move, when your kids are older the woods will just be a distant childhood memory instead of the setting for all of their growing up years. Staying right where you are makes perfect sense.
Is there any way you can "separate emotionally" while living in the same house? Start living like a single woman emotionally. It sounds like you live pretty much on parallel tracks as it is. What if you plan a strategy that focuses on taking care of you and the kids. Cultivate friendships with other women around you. Pamper yourself physically. Take care of yourself emotionally and spiritually with reading, meditation, lots more music.
What if you just make a vow to yourself that you will not "get into it" with him, no matter what. Don't rise to the bait, no matter what he says/does (short of physical violence). In other words, stop trying to get him to come around. Stop trying to make him be different. Just accept him as he is and accept your relationship as it is. Cut down on the stress level. Back off and leave him alone. Accept that this is an imperfect situation, and that you are choosing to stay in it for good reasons.
For example, the thing about the keyboard. Let him move it. So what? Does it really matter all that much? Was it worth a fight? For this system to work you have to swallow your pride and give up the notion of being right. Chores, tidiness, noise-- whatever he rants about, just let him. Go about your business, be kind to him, but tune him out.
Can you carve out a life in that house for you and the kids with minimal pleasant interaction and NO hostile interaction with your H? No, it's not an ideal solution, but leaving with the kids sounds like it would do more damage to everyone in the long run.
I wouldn't discount the healing, nurturing qualities of those woods and your great neighbors.
