Because of our connections to each other, assisted suicide is far more than a personal decision. We open the door to accepting a doctor killing a patient. It will eventually lead to voluntary euthanasia, then to euthanasia by proxy, and on to involuntary euthanasia. Doctors will decide who deserves care and who deserves death.
It has profound impacts on our faith as well. Our bodies are our very selves, not some separate thing that we can manipulate however we want.
Here we have a growing number of resources dedicated to the spiritual aspects of illness, suffering, dying, and death based on magisterial teaching. May you find knowledge, comfort, and strength in these resources.