Oh yes, time heals. In fact, you'll feel much better once she starts calling you crying and saying she's sorry. You are right: its all about her--your feelings don't matter. So, when she calls (and she will) stay strong. If you really want to teach her a lesson so she'll think twice before cheating on a nice guy say this:
"I'm sorry but I really never want to speak to you again. You have no integrity. I can't date a woman who is a cheater, I deserve someone better." She will sputter and be indignant, but only b/c you will have hit the mark squarely on. Then wish her well and hang up. Don't answer her return calls.
I promise you will feel MUCH better after this. Post here and tell us how it goes.
Second thoughts can generally be amended with judicious action; injudicious actions can seldom be recovered with second thoughts.
--Cyteen by C.J.Cherryh