Oh, yeah, one more thing...
"All I hear is him saying I'm doing this to us"
It doesn't get more obvious then that. Trying to put the blame on someone else is a huge coverup mechanism, no matter what it is we're doing that we shouldn't do. It's a way to try to psyche the other person into thinking they had it all wrong. I know it's easier to believe this lie than to acknowledge the truth as your mind knows it.
Ask yourself the following question: "What evidence do I have of him using?" not just my instinct, but if I was to sit back and watch the situation from outsider's eyes, would I still think he was using? Does he have a different appearance when he comes home? I don't know what the signs are for Meth, but I know with Heroin the size of the pupils change, and their voice even slightly changes. They sound a bit like the turtles from Finding Nemo... their voices get really deep, really soft, and the speech gets really drawn out like that. Figure out if your husband ever has anything like this going on when he comes home... if he is truly using, there will be obvious signs of this type, if not the same ones.
Is anything missing from your home? Anything valuable?
Are your kids coming to you and asking questions about why daddy is acting so funny, what's up with his funny smell, etc?
Like I said before, my experience is with heroin, so some of these questions might need to be reworded a bit to fit Meth, I really don't know (though I'm sure others here might could help with that), but what I do know is that you can play the what-if game with us all day and all night, and even if you get 50 people who say that they don't think he's necessarily using, it doesn't change whether he is or is not. Only you are there with him... we can go by only what pieces of info you give to us.
Just know that you, your children, and your husband are on my mind. I truly hope that you find the strength and resolve to see and respond to the honest truth, whatever that may be, in the safest way possible for you and the kids.
*hugs*