I am so sorry that you are having some issues w/your xh. I wouldn't involve a third party. Why? Because your business needs to stay between the two of you and you certainly don't want the "he said/she said" business around town, even though you may trust the "third party".

The only contact you should have w/him is about the children or bills that he should be paying. You don't have to "maintain" contact w/him just to play nice...state your facts when it concerns your children/bills and leave it be. Document if he gets nasty and keep your emails and text messages and if it becomes too much, you may need to let your lawyer know about it.

If you are still allowing his actions/statements to get to you, then you haven't detached enough.

If you need time to yourself, then take it...you don't need to tell him that you are going NC...just do it. Actions speak louder than words. Answer he texts if they are necessary and/or an emergency or require an answer...otherwise, there is not need to respond to them unless you think you need to. Take back your control over your life. As long as he knows that he can get a reaction out of you, he will continue this behavior.

Sit quietly, the answers will reveal themselves when you least expect them to.
The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.