New here but learning slowly. Advice appreciated

[Albuquerque]

Here's a question for some of you. I know that H has OW. He had an affair almost 10 years ago so I recognized the signs, but there's also been a LOT of other obvious things I've noticed. It's almost like he's not working that hard to try to hide it. I have no plans to tell anyone nor to necessarily "confront him" about it. However, I dislike NOT being honest. He's leaving next week to go to her city and although he may have some real reason, I know that's not the main reason. I've thus far feigned ignorance but I can't help feeling like I'm being dishonest with myself. I know the truth. I'm dealing with the truth as best as possible and with patience I never thought imaginable. But I feel as though I'M lying to HIM by not revealing what I know. I'm trying to think rationally about this and can't quite get my thoughts straight.
Should I let him know I know? I wouldn't do so in a blaming, confrontational way. Just the next time I see him tell him that I don't feel it's right for me to keep secrets and I know about OW. His life is his to live and mine is as well. I choose to keep mine free from secrets.
But then on the other hand, I don't know what the benefit of that would be other than making me feel better. Although that is a benefit that is worth something. What is the general recommendations for this issue?