my husband

my 56 year old husband was diagnosed with lung cancer in april of 2010. since then he has had two surgeries, followed by radiation to lungs. things were quiet for 9-10 months. CTscan showed lymphnode involvement in chest. started 6 weeks of radiation but only got through 1 &1/2 weeks of this when he ended up in ER with severe headache vision changes and balance issues. I prayed it was a stroke! no such luck! metastisis to the brain. they immediately started full brain radiation(12 treatments) followed by stereotactic radio surgery to 3 tumors in the brain. This knocked any bit of life out of him! he has lost his hair, has absolutely no appetite, and I have to force him to drink carnation instant breafast and anything liquid. he is smoking again! and just sits or lays in bed it has been over a month sinc his full brain radiation! I am struggling with his lack of fight and lack of interest in his life. and mine.
they were going to go right into chemo but the ct scan showed with 7 treatments to lymphs, there was some improvement. so we start the radiation again tomorrow.
I need help understanding what he is feeling. and he won't talk about it.
Am I wrong for being angry at his lack of interest in his treatment and life. help!