Try to keep on a peaceful even key. Fake it until you make it.
Let the affair run its course. Don't have your own. Don't necessarily be very predictable and boring, but don't go out and get revenge or start up something with someone else.
First thing...take care of yourself.
Sleep. Walk. Eat. Breathe. Relax.
When the drama starts. say to yourself Peace, be still.
Then let yourself be still.
Only act when the prodding comes from peace and stillness. Not from drama. Don't react to that.
sg Love is PATIENT, love is KIND, LOVE never fails / DB since 2001