I'm trying to release with grace because we have a teenage son and NC wont work. But I'm really not up for it. I'm very tense, defensive, guarded, sometimes critical.
Is your need to "run" more about you than him?
I would think that since you share a son and you were together 16 years, that having an amicabe relationship is best for everyone.
You expressed concern about the suicidal ideation - I think here, too, cutting him off cold is actually riskier than slowly dialing the relationship back. You should talk to a DV counselor, this subject has been well studied and there are thing to do and not to do. In general terms, you want to affect separation and not heighten emotions if you can. You sound "burned out" - getting others input and coaching will be helpful.
Have separation agreement of sorts as to what is OK and what is not OK is a really good idea. If you can agree to some constructive ground rules, it can take a lot of the "feeling each other out" out of the relationship. Simple things like no unannounced visits, waiting for call and texts to be returned before sending another, etc...