As you and your wife know very well, this disease causes families to lose their loved one not once but twice. Times 2 in the case of your in-laws. They were lucky to have had you and your wife to step up and care for them when they no longer could. I always tell the caregivers in a family that they now have to funnel that effort into themselves and feel good about it (it's not as easy as it sounds). You've both earned it.
Just saw this thread today. Sometimes we are lucky enough to discover our earthly purpose, and the fortitude to see it through. I hope you also find your reward. Prayers for you folks.
Thoughts and prayers to you and your family Longbow. You've been through the wringer with all this for sure. May God bless you and your wife for all your good deeds.