Pearly I understand you.
Your gut tells you everything you need to know.
No your instincts are likely right, you are especially sensitive to red flags so if you feel something is up, it might very well be.
Your emotions are stirred, the lies are still there, likely the most important thing for you is to protect your peace.
The "I do not know how to confront him" could be a "I fear that if I confront him I will have the confirmation of my instincts" is this possible?
If yes, then you know the path that awaits, he will feel confident he can deceive you, go in the mud deeper, do more damage.
You feel what is best inside yourself, so follow it. As an external person I would suggest you to confront him. Your senses are sharper than 7 years ago, even if there is denial you will feel it. And you can start to take cover to protect your life.
It is up to you.
About keeping the guard up, unfortunately is useless.
If a partner wants to cheat he will cheat.
Work is not a safe space (on the contrary is where a lot of betrayals happen).
My wife did it, I know for a fact that if I ever wanted to do it, that would be the easiest place to cheat. No way for the spouse to prevent it, the only thing stopping that is a partner who is faithful.
So those excuses of him about long hours will not hold.
At this time I hope you will find the answer to what you feel you need the most.