My husband and I went through that about 5 years ago. There are a few books that saved our marriage:
The Five Love Languages - Garry Chapman
Fall In Love, Stay In Love - Willard Harley
But the most influential was:
Surviving an Affair - Willard Harley
Some things I learned were:
9 years is a long time to get to know someone. Who's to say that if I started over, it wouldn't be worse next time. At least I knew him...right?
Marriage is not about the warm fuzzies everyone talks about and leaves because they are gone for. Marriage is a promise that no matter what you will be by eachother's side to lift them up when they fall -- whether it's you or him.
You can get past this and have the most amazing marriage you've ever dreamed of. You just have to care enough to work on it. Professional counseling is great too because it is a neutral safe place to work out the issues that have been created by the indiscretion, and a great place to find out what led to it.
I wish you all the best, and if you ever need to talk to someone, you can email me and I'll give you my phone number. Hang in there!!
You'll be OK. :-)