You have been a busy man during your lifetime. I understand your concern about your wife's treatment of your older daughter. I hope that now your daughter is in college she is living away from home. Does she not treat the 2nd daughter the same way? It sounds like you are getting very little emotional support from your wife or love for that matter. If I were you I would seek counseling for yourself and see if you can come to terms with how you are feeling about a divorce. Then maybe you can make a wise and informed decision.
Good luck to you.
Gayle