I have not really tried to have minimal contact with him for longer than a day or two. How would I explain that without him thinking that I am mad at him?
You don't. Let him wonder what's up -- be mysterious. If he asks directly, you respond with positive PMA; if you respond at all.
That's why it works. It draws the other person toward you because you're pulling back.
ME: 38 BF: 40 T: 10y, no kids, no M (by choice) BD: 7/14/14, BF admits to PA, wants out, lies about new R. 10/1/14: I move out, BF lies about move in with OW 12/4/14: OW confronted, reveals all the lies