Dear Kaleidoscope Eyes~
Welcom here to the Forum. There are quite a large number of people that have been in your position and really find it difficult to know what to do.
First the reason for stopping , looking in from the outside I would suggest the first reason he gave, that it was a waste of money was correct. The fact he went on to say that you would find out -presumably due to the credit card charges would probably have been an influencing factor too.
Porn addiction is just that, an addiction. It will probably have started due to various reasons, and perhaps they are still there, and perhaps not. It has however become a way of life for him.
Visiting a sex worker on the other hand does seem to indicated matters have escalated. For him to say your should move on is all very well, but he is the cause, not the person suffering. He has kept this secret from you all your lives. He may want it forgotten and life back to before, but that's not on.
Frankly from my point of view the worst thing of the lot is dishonesty, to lie to you for all those years, which makes it so much harder to think you can rely upon him in the future.
And it is real suffering for you. Many partners feel a great sense if inadequacy, betrayal, mistrust, loss and grief and anger too. In relation to the inadequacy the only thing I can say is nobody really can compete with porn, as it is an unrealistic fantasy, and if allowed to take over, as it has been here, it is no wonder your marriage had suffered as a result.
I'll just mention at this point that any addiction can only be 'cured' with genuine determination, outside professional help, maybe a support group too, plus support from those at home or in his life too. There are no guarantees and often setbacks.
If as you say you both want to stay together it may well be a case of often having these incidents in your mind as now, and wondering if they have recommenced.
May I suggest you insist he discuss it fully with you as one of the preconditions to remaining together, along with professional help. They might help you to decide if he is genuine.
I'll also say that people are not one-dimensional, please consider if he has other strengths or on the other hand faults, that will help you see him in true perspective.
I'm sorry to be blunt, but choices of living alone, or with someone who may well revert are hard ones to make.
Please let me know what you think, have I laid out all the considerations or are there more?