Sorry, not too sure what your question/point is. You seem to be adjusting to the degree in which you are "out" and making accommondations for areas that need caution, i.e. your father in law. It really is your decision...accept the risks and tell him or leave well enough alone. Why do you want to tell your wife's mom? Is there a chance she will see you? Is she local in your community or does she live some distance away? Was the separation from your father in law amicable such that she might tell him and then you will be out in two ways? Think about it.
Laura