Oh N., I feel for you so much. You must be just mentally and physically exhausted. It is unfortunate that most men do not truly understand the extent of things that we do for the family, for them, for the children, and for the household. And when we spill our feelings out and let them know what we need, it goes in one ear and out the other. It's the Y chromosome girl. LOL Just a little humor there, but not trying to make light of this, because it is truly something that men should really pay attention to. They do not know what they have until it's GONE. Most people don't realize that. We all make that mistake I think.
Sounds like you have tried everything, and you're right. Therapy will not work if only one of you is going. Family Therapy is vital in situations like this in order to rebuild a strong foundation. May be ask him directly what he wants out of this relationship? What does he expect of you, where does this all leave you and the children? Where do you stand with each other...vice versa etc. If he won't sit down with you and talk about all of this, then all it will do is fester and it will end up blowing up. Men, even though they work and they are not around the house and family much due to being at work; also feel the stress of being a parent. And with his job, being an Officer, he is truly dealing with dangerous situations every day. It's got to take a toll on him. I'm not excusing his behavior, but merely pointing out that this could be what he's feeling. Most men don't know how to release their feelings into words. They have to veg out (play xbox), in order for their own 'down time'. My husband plays computer games in order to relieve stress and have down time. It works for him. Don't know how, but he says it does.
Take some time away from the situation and allow yourself this break so you can come back to it with a fresher mind, and perhaps a different perspective on things. Then approach him about family therapy, or even just talking with each other and allow each other to vent and tell one another what you need out of the relationship. And do your best to give that to each other. It takes a lot of work. As the years go by, as time changes, we too change, and sometimes we end up going separate ways, instead of embracing that change together and going with the flow of it. It's definitely easier said than done. But it can work, and it can be done if both parties are willing. He loves you. He may be at a loss too as to how to go about things. Men have such a different way of dealing with issues from us women, and it definitely can lead to conflict.
Hope this helps you. Think about what brought you all together in the first place and share that memory with your hubby...with a smile, with an 'i love you', and share with him what you love about him, what attracted you to him. Keep it positive. No "buts" in the conversation, and no 'negative' comments. Keep the positive energy and it may lift both of you up. :-)
HUGS to you!