I would not say he is bipolar or you wouldn't have
wanted to stay married to him and those signs would have
been there all along rather than upon his leaving the relationship.
But really, he isn't your problem anymore. I would hold your ground on the divorce and any child support (let your attorney know about the car) but I'd also begin paying LESS attention to him. You shouldn't know about his shopping sprees or where he is staying (back and forth with lady or parents, etc.), etc.