Masturbation in and of itself is not cheating. If, however, you are looking at porn or imagining your neighbor naked while doing it, and are doing so behind your wife's back, then that is, at a minimum, emotionally cheating. It's no different than if you talk sexually to a girl online behind your wife's back. It's cheating.
As for counseling, I know full well that if someone doesn't want to change, then counseling isn't likely going to help. But that doesn't mean I have to sit back and accept my partner's refusal. If my boyfriend became addicted to drugs, there will come a point where I tell him that he either get counseling and work to overcome his addiction, or we're through. It would be no different if he chose to withhold sex from me. If he's not willing to change so we can reconnect sexually, then we're through.
Also, it doesn't matter if a lot of minds would change if they were in that situation. Nor does it matter if most people responding haven't ever been in that situation. If you go behind your wife's back to have sex with someone else, then you have cheated. Full stop. End of story. You may get a lot of people who will sympathize with you on why you cheated, and many may agree that they would do the same thing. None of that changes the fact that having sex with someone behind your wife's back is cheating.
