It's good he is going to seek professional help. With several addictions, they probably have to be addressed separately, although the compulsive nature of each is similar to the others and addressing compulsiveness as a behavioral disorder is also a good approach, although I'm an amateur shrink at best.
I understand your viewing the relationship as "friends" as this point, but is it really possible? Perhaps I'm splitting hairs and what you are really saying is that you are going to practice detachment and not take any of it personally.
I have been there with exah with the alcohol coupled with a pornography addiction, and I think they fuel each other, and the guilt from either can lead to them wanting to do the other. Likewise, alcohol is an uninhibitor, so to speak, and surely opens the door to the obsession with inappropriate conduct with other women or pornography use.
No doubt looking at the world from a sober pov, it will be easier to address other compulsions/addictions.
But...my question to you is: are you taking care of your needs? Including all your emotional needs?
He has never officially "cheated"...or never been caught? Drinkers are not usually the most honest of people. I hope he has drawn a line there. If he works hard on himself, you will hear any confessions that he needs to make, hopefully. I don't mean to make you paranoid about that, but a drunk businessman away for days that likes to chase women when intoxicated doesn't sound good.
I would ask, for my needs, in your situation, that he stop turning off his phone and answer my calls whenever I called. You can try to detach emotionally so as to not add to the mix, but a husband answers phone calls, period, in my book. I too have boundaries and needs, and answering phone calls fits into this category. Are you ignoring a need of your own to know where he is at and what he is doing?
It's alcoholism and mental illness...afterall, alcoholism is a mental illness, or a symptom of one, take your pick, end conclusion is the same.