You are still learning also, but you are doing great. Keep asking the Lord what you should do because they both need to know the Lord in the same way that you do.
That is the only way she is going to be healed from the pain that she has suffered from the loss of her husband. That way, she won't make the same mistake again by going after what isn't hers and then having to suffer the loss when they go back home.
Definitely share with him the same thing that you have. Even if he doesn't accept it right away, he will. One day he is going to look up instead of down all the time and you need to be the one that shows him the way.
That is what you are called to do at this point. Help him to find the same peace that you have so that he may heal from what he has done. That is the only way that he is going to know that he is loveable inspite of what he has done.
Remember the release and the peace that it brought you when you figured out that no matter what your mistakes were, you were loved. You were loved so much that he died for you and he died for them too.
You are doing great Cathy and there is going to much work to do in order to get to where the Lord wants you guys to be, but it will be worth all the work.