When I see the abuse is coming, is it better to let her cycle through it or just walk away and let her be angry?

lulu12, I get what you are saying. It could have been me writing what you said. It is frustrating to say the least. The anger, manipulation, walking on eggshells. Not to mention...the having to always walk away and having to always be on the look out when they turn on a dime.
Mine sets me up to fall all of the time. Read some of my posts.
I don't know how to answer her multitude of questions because they are little time bombs waiting to be twisted and turned and picked apart only to end in some lame argument.
I am coming to realize after a lot of soul searching that she really, really isn't aware. Sure maybe some of it sometimes, most of it now and then, but it isn't her intent. I think if she could let me know she loves me she would be giving up control. The one thing they have is some kind of control problem. She has out and out told me-'you're not going to break me!!' I'm in a constant state of mourning. And if I could be in 2 states of mind at one time-the other would be ptsd.
Just want you to know I hear what you articulated. I'm sending you positive thoughts and hope you take care of yourself and your own self preservation. hugs

I don't mean to sound impatient but no, I'm not making much sense of what you're trying to describe. Could we take the latest incident as an example? - and you can correct what I've got wrong/fill in the gaps.

Your mother said she did want to go somewhere - where? - and she wanted you to take her.
Then, a dispute arose over..? What? What was the bone she decided to pick?
So having engineered this dispute, she then had a paddy and stormed off.
So the trip was cancelled.
You think she got her way because she hadn't really-and-truly wanted to go.
You told her that.
She disagreed with you. Vehemently.

If you want to continue this living arrangement then at the very least, when the first sign of her anger starts to show, walk away, drive away, whatever to not give her an audience for her tirade. Clearly the tactic of sitting silently only infuriates her further, so when you see the anger coming, get away quickly. A quick “we’ll talk later when you’re not feeling so upset” if any explanation at all, but please don’t stick around being berated and in fear of being hit. No one deserves that

A simple answer to the heading question, do what is better for you, probably walk away. You can't please her or make her brain better.

If it’s been a while since your mother visited her doctor, she needs to go. Before she goes, you need to write a letter to the doctor and tell him/her what’s been going on. Mom may be physically healthy, but she is not mentally healthy.

If at any time she becomes physically abusive with you, your son or even your dog, call 911. When you explain that she has become physically abusive, they will evaluate her and treat her.

You truly need to take charge of this situation and stop trying to placate and mollify her. She has you under her complete control. You need to get to the point where you will not allow her to emotionally abuse you.

You always have the option to move. This doesn’t sound like a pleasant living situation for you or your son. You have an income and could afford an apartment. See an attorney to figure out how to handle your half-ownership of the house. Tell your mother if she needs help she can hire home health care.