Hope no one who has been cheated on reads this article. This isn’t about sex, it’s about betrayal and the betrayer holds all the responsibility for their own behavior. The betrayed person has no responsibility to be calm or worry about the feelings of the betrayer.
See a marriage counselor, sure. Reflect on what, if any part you played in your partner WANTING to stray (are you an asshole, cold, withhold sex?).
But the actual betrayal? That’s on your spouse and you can and should be as angry as if they burned down your house and spent all your money.
Lots of people feel like committing adultery. But no one has to follow through with something they know could destroy their marriage and their partner.