I want to address the fact that you are feeling so disconnected and having thoughts of divorce and not sharing those thoughts with your wife. I know we shy away from hurting others and you are aware of how hurtful it would be to her. I think, though that you are taking away any chance she might have of finally doing something constructive about the problem by hiding how you are feeling now.
I doubt seriously that your wife has ever been honest with you or herself about her low sex drive. It's not a problem she will ever solve unless she is willing to be honest. By withholding how you are now feeling you are moving further away from a solution and beginning to play the game the way she does.
Sometimes people have to be shocked into facing themselves and their problems and finding answers. Sometime we have to be willing to let people we love experience emotional pain because as devestating as it is it can also be a great motivator for healing one's problems.
Your love for your wife is slipping away from you. Giving her a glimpse into that fact may be the solution you have been looking for, for all these years. She is complacent....trying but putting the wrong kind of effort into it. He main objective is to not have to deal with your anger over the subject. I have to wonder how she would react if she new that dealing with your anger was the least of her problems? Cathy~