Angry, exhausted, and looking for realistic answers - GBMIV caregiver

My mother-in-law was diagnosed in February of this year with an inoperable GBM, stage IV. She is 60 years old, and is also an insulin dependent diabetic, has advanced COPD, and advanced heart disease. My husband and I drive four hours each way every weekend to provide my father-in-law with respite care, as the medical bills have left him unable to hire in-home care.

Before I get into this details, let me preface. I have always thought the world of my mother-in-law. We have had a wonderful relationship, and have enjoyed many happy times together. My husband as well, has been very grateful for her presence in both his own and his father's life, as she brought laughter into their home after his mother's very sudden and tragic death when he was teenager.

Since my MIL was diagnosed, she rapidly ceased to be the person that I knew. The tumor is located in her brain in such place that it primarily affects her short term memory. Until this experience I had no idea how much of our indivdual personalities are defined by our most recent experiences. Most of our visits revolve around what my husband and I have come to call the "litany of the dead". She gets stuck in the round of questions of who in her family is alive, and who is dead. This can go on for hours, with the same 20 family members, and attempts to kindly lead her in a different direction are almost always redirected back into the loop. She doesn't know what day it is, how old she is, where she is (living in the house she's been in for 20 years), she's forgotten my father-in-law and the loving relationship that they have had for these last 20 years and is thrown back into the fear and anxiety that she experienced in her abusive first marriage. She doesn't sleep at night because she doesn't know whether its nighttime or daytime, and her addiction to cigarrettes compels her to chain smoke as she forgets as soon as one cigarrette is out that she has just had one. She no longer can cook or sew - two things she dearly loved to do. She can't do crafts because she can no longer follow simple directions. In short, she seems to be simply a shell of a person, existing completely and totally in her confusing and terrifying present.

She has had radiation treatments, as much as she can safely be given. She has been on chemotherapy for 8 months. We have prepared ourselves for the inevitable end that we have been told by doctors since the beginning would be coming. My father-in-law has aged 10 years in the past 8 months, and his health is declining from lack of sleep. My husband and I have put both our careers, hobbies, and other obligations on hold - all the things that make our daily lives enjoyable - and are burned out to the point of exhaustion. She has been slowly, but progessively declining, all the while trapped in a mind that no longer functions correctly. I am horrified at myself, because I find myself just wishing it would all end.

We have had no hope throughout this process that she would recover. The rounds of chemo were simply hoping that she would regain enough of her memory to be able to have SOME quality of life, rather than existing at the whim of her base emotions. My father-in-law continues chemo against the wishes of her son - an EMT and firefighter - simply because he can't bear to be the one that decides to stop treatment. Now suddenly, there has been a slight improvement in her memory, although her motor skills have declined and her body's ability to regulate its blood sugar levels - even with insulin - seems to have become wildly unreliable. Has anyone heard of a GBM, stage 4, inoperable patient, suddenly getting better after 8 months of failed treatment? Are we looking at a possible remission? If she does regain her short-term memory, are the memories that she had previously - of her family, of her loving second marriage to my father-in-law, of the weddings and births and happiness - lost completely? I am fearful that this slight upswing is just a delay of the inevitable... another drain on the already strained resources that my father-in-law has as well as on his own fragile psyche, and more importantly prolonged torture of my mother-in-law. What have people experienced in the end stages? How have people coped with the feelings of frustrations and impotence associated with prolonged caregiving?

Thank you all so much for the opportunity to vent, and for any responses you may have.