I am SO sorry for your loss. My heart goes out to you.
You must *immediately* stop feeling guilty -- for two reasons:
1.) THEY are the experts, THEY are the ones that studied, went to Graduate School, etc. (you've seen the TV shows where doctors stay up all night doing residency, etc., heck, one show has this doctor sleeping in the broom closet of the hospital because he is made to learn and work so hard).
You are *SUPPOSED* to rely upon them, you are NOT the one that walked over to the Medicine Cabinet and said, "Hey, I think you should give him the stuff in this shiny blue bottle over here..."
THEY are the ones that decided what/when/how much/which medicine to give.
So you are NOT guilty of anything!
2.) Read up on methadone -- one of the main side effects is a warm, fuzzy sleepy "euphoria" where people describe being floating in a glorious blanket of warmth and peace!
So, maybe tell yourself that while your husband was suffering from 'whatever' it was, it was probably the METHADONE that gave him peace and relief!
If you could speak to your husband in heaven right now, he would probably say, "Honey, quit feeling guilty -- the methadone is what made me feel GOOD during my last few hours."
Please read, and reread my post.
In my final hours, I hope they give ME methadone.
My condolences.
I don't quite understand why you feel guilty.
Hospice does its best to prevent suffering from the pain of cancer, and methadone is an excellent pain medication.
Morphine is preferred for the treatment of COPD because a doctor can better control its effect on breathing, however, both morphine and methadone work in similar ways -- it is just that methadone suppresses the breathing longer. At end of life, it doesn't matter much which medication you use.
If your husband had an allergy to morphine, then methadone is definitely the proper medication to give.
Death is not often a pleasant experience, especially death from lung cancer. There is nothing to blame yourself for. Your husband's death was inevitable, and chances are that no medication could have reduced his suffering at the end.
Please forget your guilt and move on into your grieving. Again, I am sorry for your loss, but from what you report, there is nothing else you could have done.
Be in peace.