If you are really and truly at the point where you cannot do anything more WITHOUT his being on board and working with you, then I think that you owe him a very frank and honest discussion. He needs to know this. He needs to know that his marriage is at stake. He needs to know that if he fails to take action, then he will lose you permanently. He needs to know exactly how you are feeling and where he stands with you. He can't take appropriate action without a true assessment of the situation. He needs to know the exact price he will pay for inaction on his part.
Delivering such a message will require some quiet time, away from kids and family and other distractions, and you will have to be able to remain calm and matter-of-fact throughout -- even if he becomes angry and defensive, DO NOT do the same. He will probably criticize and blame YOU for the problem, and he will not be able to understand why the hell you can't just be happy with the current arrangement -- why are you stirring things up?! Stick to the FACTS, and don't blame, criticize, or get angry in return. Simply stick to your guns and make sure he gets the message loud and clear from you.
Also, don't be too fatalistic about the fact that you're having a hard time desiring him right now -- that's a symptom of your anger, resentment, and the extremely disconnected relationship that you have right now. If he works with you to reestablish that connection, and help you work through the anger and resentment, I have no doubt that your physical desire for him will return.
Just my thoughts (and short, for once)
-- B.
Me 50, W 45, M for 26 yrs S25, D23, S13, S10 20+ year SSM; recovery began Oct 2007