You ask a very important question. How do you get over the anger? And I might add, the distrust.
It is very difficult. You have to look deep into your own heart to do it. It's not something that happens quickly, and I know I thought as much as I wanted it, I thought it might not happen at all. It helps a lot if the spouse expresses real remorse for the pain inflicted. When you can believe the spouse, as Puppy described above, that helps. And of course, there are the old good times to consider, and new good times that are happening. For myself, I had things I regretted too, so I had to be realistic about blaming.
And then there is time, and there is change. My H and I worked on reconciliation through the Retrouvaille program (www.helpourmarriage.org) and they taught us skills for talking to each other in new ways and taught us how to change to be better spouses. Unless we changed ourselves, both of us, and changed the way we interacted, I don't think true reconciliation would have been possible. Going back to the same old marriage is not desirable. You do need to create a new and better marriage.