I totally understand your sense of betrayal. It was incredibly hurtful, and for her to describe it to you can't have helped. Your rage is perfectly understandable.

But wait. You have a girl you've clearly been very keen on. There's lots of things about her that make special. What's more, she clearly loves you to bits. AND she's delighted to have you do the things that really turn you on, not least, spunk on her gorgeous smiling face. She made a really stupid mistake - she's admitted it and begged for fogiveness. To me she still sounds like a real keeper. Explain how you feel and how angry you are. And then get her to slurp, drool and suck on the cock she really likes - yours - and decorate her like a cake as often as you possibly can!