SteveH,
I read the entire thread, but one thing you said really sticks out, the part about thoughts of divorce. Your real issue seems to be staying in the marriage because of your kids. If you didn't have kids, it seems that divorce would be more appealing to you.
I think the situation should come down to if you really still
love your wife and want to work it out, or if that love has evaporated and you feel trapped because of the kids.
After five years of no sex, no intimacy, and no bonding, that love has to have lessened as your frustration has grown. Porn isn't an outlet, it's simply a stop-gap measure. It won't make you happy or cure your wife's sexual problems.
If you really love your wife, do as Jespah mentioned, find a NEW counselor and give it one more try. After that, or even barring that, seek an amicable divorce. Kids are resilient and you'd be amazed how well they bounce back especially when they realize that both you and your wife will still love them and the world isn't coming to an end.
Remember this too, at 44, you are NOT in your dotage. Your kids will grow up and leave and have lives of their own--that don't include you. We only have one life and we need to live it. I don't mean to say to abandon your children, I've an idea you'll spend as much time with them as you are able which is honorable and good. What I am saying is that you deserve your own life. Sacrificing your own future for them will only lead to bitterness towards them and it's not their fault.
Try to find a happy medium here. Make a full-scale attempt and then move on.
Best of luck to you SteveH