Ill start by saying going through your daughter was a shady move, not good. I'm guessing she reached a point of desperation and acted accordingly.
The thing I disagree with is having relations with people of the opposite sex. It never tends to go well, and can certainly foster insecurity in one party. Did she also commit the same actions that you did on social media? Did she have lots of male friends that she communicated with?
Walking the line between not caring and caring enough is tricky. From how it sounds, you were firmly on the "one foot out the door" side of the line, thereby never giving her any sort of certainty in the relationship. Without a firm footing, she resulted in desperate behaviors.
While I do agree that she was out of line, it would likely be beneficial to evaluate how your actions drove her to behave like this.
Personally, a fair amount of jealousy doesn't bother me. It serves as a reminder of the power dynamic in the relationship. If she stopped caring about me getting around, then she may be looking elsewhere as well. Very telling. When my lady gives me grief, "so who's xxx at your work?", I usually respond with "some new girl, young, very attractive, I wonder if she's single...?" That's usually the end of that line of questioning...
