First, I am glad you got your son squared away. Hopefully he won't be doing that again.
Secondly, I second leahsue. Man, you are so enmeshed with her every move and mood and action, and deviation...... It has got to be exhausting.
You say she drove by his hangout on Sunday morning. Where does one hang out on a sunday morning? A bar? church? A Diner? What hangout is this?
You all live in the same town I take it. And if you keep tracking her routes and mindreading why she may have taken them, you are going to make both of you crazy.
She is either going to chose to run to him or not. You tracking down her every move won't stop her. If she wants to, she will. And you will find out. But you are going to burn yourself out.
Your son's had some big life events going on, yet that was all about how those events might affect your W's waywardness. Sometimes, you need to focus on what is important in the moment
