Once a cheater, always a cheater. That’s why I never took anyone back after they cheated on me. Fool me once, shame on you, fool me twice and all that

Better all alone than in the wrong company.

I mean, yes. Technically, giving him a second chance is your fault. But don't blame yourself too much for wanting to have trust in someone you love. Just learn from this and guard yourself better in the future. Also, whore or saint doesn't matter, your man is still the one who stepped out on his marriage.

If someone cheats on you, it's best to cut them loose and not look back. In time you may forgive them for your sake but don't give them another opportunity for mischief.

It's definitely not your fault and you didn't do anything wrong in choosing to give him a chance, he made the wrong choices and actions.