Do i need to leave him or stay and work it out?

I separated from my husband cause he was flirting with this one woman on an app.

We separated for 2 weeks, on those weeks, he was emailing me to come back, like i got over 100 emails from him. I decided to move on and not read or respond to his emails anymore. So i changed the email to my password, to avoid getting in to read his messages. I ended up having to call him, regarding our kids, and i ended up going back to him.

Just today i got access to my email, and decided to read all the messages he emailed to me. And on one of them, he emailed me 2 photos of a woman. Now it makes me feel like hes been cheating on me since, i just had no clue.

If ive seen this email when i was still away from him, i wouldve never went back. What should i do?