Haven`t much advice to give. Just have to say I admire you for being a rock for your kids and for managing to pursue your dream by going back to college.
Glad your inlaws are so supportive but also that you`ve decided not to talk about W and her actions. You don`t want to do anything at this point that will make it harder for her to come back into her kids` and parent`s lives. She should already be wracked with guilt for rejecting them.
You will begin to feel much, much better when you start to detach.It will help everyone around you too.Keep checking on in here. This is a one day at a time job and you`ll have lots of support here to help you through each day.