> morphine or any way to avoid confronting death is as cowardly as opting for suicide, since it is accelerating the process of dying.
You cannot accelerate the process of dying. You'll die the day you have to; not earlier, not later. Every day of your life is counted. I'm not justifying suicide, of course, for suicide is definitely a sin: the sin of murder applied to oneself.
Think about it this way: When Jesus Christ was on Earth he healed a lot of people from a great deal of diseases. This diseases, of courses, were painful. So Christ himself relieved pain. It is, therefore, not a sin to relieve pain.
It would be a sin if you were to take opioids for pleasure, for it is clearly written that drug-addiction is a sin (cf. Galatians 5:20 -> φαρμακεία, /farmakeía/)