No, never divorce. Tell her that you love her and will forgive her for the incident. After that, just stay cool, and move on. See for the year ahead, is she change inside??? Mostly woman will get touched in heart just by you forgiving them.
But, if she change none after you declared that you love her and forgive her, so, maybe it is the time for divorce.
The plan B:
If you can handle this, you are a great man, so just forgive and forget. Remember the bible and what Jesus said: Forgive your enemy, pray also for the man your wife cheating on. It will release your emotion beautifully.
Remember, many people might have worse marriage condition than you are, so be grateful if your wife showing a pity face, and feel sorry to you, it is better than a rude woman who just leave you with her new bf. (it is happened in my country, there's one actress who cheating and just leave her husband).
Maybe my problem is worse than you, I have problems with my parents, they're not compatible with me. In my mind, my condition is worse than yours. Think openly about the dark side of life, ok. Let's move on bro!!! Forgive and forget, life is too short to fill with anger, rage, envy. Make your life useful and satisfying you. Start do many things which will satisfy yourself. Love yourself first, than the others. It will heal your soul too.