That Cheating S.O.B.!!

So lastnight my husbands side chick messaged me on Facebook basically telling me the truth about what had gone down between them. I confronted him this morning and he says "She's crazy and that stuff didn't happen." Needless to say she came with receipts, pictures, screenshots and a flight itenerary. I'm physically sick. I can't stop shaking and I want to kill him. We are on vacation at his parents house in San Francisco and I am so distraught. Leaving him isn't a question, that's certainly what's happening when we get back home.  I just don't know how to control my feelings because I want to bash his head in. Please keep me and our 6 and 1 year old in your thoughts.