Even though you are in pain...your behavior is very very good as you describe it! That will serve you so well.
You are right....your situation unfortunately isn't uncommon...and women often end up feeling resentful for having to take care of all of the responsibilities for their child, even though they love their child. You are doing the right things. You will need a lot of patience with her, but it isn't too late.
One caution...sometimes counselors/therapists make matter WORSE, even if they mean well. A DB coach, because they are promarriage...and make your marriage their client can be more helpful AND end up a lot less expensive than therapy or divorce.
Michele also has other resources that can help you quite a bit: Divorce Remedy (it IS Divorcebusting, but updated)...Keeping Love Alive tapes, and the Marriage Breakthrough. If you go with Divorce Remedy, do not share it with your wife.
Hang in there....we are here for you and for your marriage. You are not alone.