How to handle a car accident is a tough call. Accidents happen for a million different reasons, and I don't consider you going to help her was "rescuing", at least not on the same level as something else. Unless she was driving recklessly or under the influence, I wouldn't put the blame on her.
Your son was in the car; you naturally put on your protective dad suit. How would you have handled it if it was only your W in the car?
Sure, in hindsight it's easier to think about what one would have said or done differently, but you keeping quiet was not a bad thing to do. I'm not sure if you did or not, but the one thing you could have done is to ask her if she was ok and if she needed anything (which I think you said you did).
As far as breaking down and crying in front of S's friend's mother, I wouldn't read into it much. It is not because she doesn't trust you or feel comforted by you, in fact I don't think she was looking for comfort. Sometimes we (women) start crying as soon as we start talking about an upsetting event, and sometimes talking to another woman feels more comforting than talking to a spouse.
I understand that you want to set boundaries and not say "how high" every time your W says "jump". I do think that this kind of conversation should take place in a neutral setting when nothing else is on the mind. You should not do it during a difficult time such as an accident. Your W was clearly shaken up from the accident. The last thing you'd want to do is to tell her that she's on her own, leading her to feel even more alone and helpless.
A few years back, I was driving on the interstate with H - going about 80 mph in the left lane, and there was a ghost driver heading right towards us. It took me a few seconds to even understand what was going on, and then I ended up quickly pulling over (to the left side breakdown lane....don't know why I didn't go to the right). The car was in the same lane as us and just kept coming, not slowing down at all, but luckily it went by us without anyone getting harmed. Though we didn't get into an accident, it still left my heart pounding for a while.
What I'm trying to say is that I agree that maybe for a good part of your interactions with your W, boundaries would be healthy and needed. But in certain situations, like a car accident, I would say that a boundary can be stretched a bit, even if it looks like you rescued her. Just my 2 cents.
Very glad to hear other developments in your life though And that trip does sound like it's needed!
And that trip does sound like it's needed!
