i think you are very brave to have gone through so much. Remember when initially your wife was having the affair you didn't really want a divorce.
If she really has kept her word and you see a real change then I think you should not rush into a divorce. She made a mistake that has worked out very wrong but that cannot be reversed. As long as she has learnt from her mistake, there is still hope.
On the other hand if you feel you cannot take it any more then you are justified to divorce.
