Hi OP
I have been in a similar situation. Although I didn't go as far as counselling the OW but I did actually pity her. At one point I even felt sorry for her, she was from another country, vulnerable etc etc. I have the same type of nature as you I think.
Then as time went on, we had a similar experience, that the marriage was boosted and things seemed to be how they used to be. I (thought) I was happier, but I now see that I brushed so much under the carpet, and instead of helping myself, I had put the energy into making sure everyone else was ok. It easier to do that.
What I realised it that I too am a 'fixer', of course it was now my job to fix everything that went wrong. And I did. For quite a few years. In my mind he had cheated on me because of what I had or had not done, so I tried to fix myself so that these things were not an issue again. I had to fix him, because after all, that is what I do. If he had a problem, then it would be for me to sort it out, get to the route of the problem etc etc. Yes, this boosted my confidence, as I had sorted everything out, as I thought it should be. I felt good. In fact I felt amazing. My life was back to how it should have been.
Until the next time he cheated. And the next time after that. OP, I just couldn't anymore. I couldn't fix it, I couldn't fix him, I crashed and realised then that really, nothing had changed. I now had to deal with the reality of the situation, which I should have done 6 years before that. I was a doormat, and he had gotten away with it once before, and so he went and did it again when everything wasn't perfect and rosy anymor when I had hit a bump and wasn't making everything perfect for him.
So, what I am saying is that yes, maybe he does have true remorse and you may be able to move on from this, but what you need to do, is look out for you. Just be sure that you have dealt with YOUR issues about this, and are not just using your new found confidence as a cover.
BUT, what I shoved under the carpet is that I just didn't trust him anymore. I pretended it didn't bother me, but now I see that it was a huge problem.
So, just a little advice from someone who has been through similar, what you do going forward is up to you, but just be sure that you are in the right place to make that decision.
All the best to you Bella.