Should i get mad? Or should i get even?

My wife and i are swingers. We work at a nursing home and have met another couple who share this life style. Their names are Erick and Amanda. My wife had the day off yesterday. When i came home from work i found my wife in bed with Erick. But no Amanda. That wasnt the deal. I dont know how to react. Should i be mad? Or should i hook up with Amanda to get even?