Has counseling been considered ? ...for her cheating on you and your taking her for granted. Also for discussing the idea and application of an open marriage/relationship and how that could work for each of you. I don't remember the stat but the counselor we were seeing gave the% of couples she/they ( the practice) see's that end in divorce. They discover during the process that they need to split.
A sad situation indeed. Trust has been shattered so anything she now says is tainted with the possibility of it being a lie or half truth or spin. And you're already thinking well beyond the infidelity and trust issues and focused on the philosophical differences in which there is no compromise.
I'd say trust your gut.
Good luck D