If she "keeps repeating" that she's 'safe' then someone keeps asking her where she is going. Would that be you?
Don't ask her where she's going. Assume that she is with OM. Don't tell her to "have fun" but perhaps use her words and say "be safe" or just "drive carefully."
The point of going dark is to remove yourself from the drama, as well as to demonstrate different behavior (not pursuing, in your case). This will take many weeks or months, depending on how long your "old" style communication was in place.
As for you moving out for a week, do it if it is for you to clear your head, but not to get a reaction from her. Show her the appropriate kindness that she has lacked, ie tell her exactly where you are going. "I'm going to stay with my friend X for a week or two--I need to clear my head."
If you're going to do this, don't be there Friday or next Monday to even know whether she is home or not.
