I applaud you for your efforts! And I do not doubt at all that you have done everything you could figure out to do to save your beloved wife. Don't give up the fight, my friend!
However, I will point out that it is not unusual for chemo or radiation to shrink tumors by up to 50% or more - but thoe are usually procedures with ever-diminishing returns requiring more and stronger treatments which result in leaving - and even creating - more resistant cancer cells and in the process destroying the immen system, which is the natural first line of defense, and damaging the major organs and rest of the body.
One thing I will pass along - oleander extract has been shown to reduce or eliminate virtually all side effects associated with chemo - with the sole exception last I knew about that it did not eliminate hair loss when the chemo drug of choice was Cisplatin.