when that time comes, set yourself up w Hospice. They will give you meds to ease your anxiety and you'll probably just go in and out and sleep. They are not there to kill you, but to bring you comfort and manage your pain.
Death itself is easy, but none of us want to die gasping for air. Start the preparation for that time to come; just a conversation w a local hospice, allow them to tell you about the process when your disease has become so unmanageable and so scary.
You'll be ok if you know "when" to call and "who" to call when the time comes.
Familiarize yourself now, rather than later and, if you have family or a nurse or a social worker, let them know your wishes.
Be well and try not to focus on the worse possible scenario.
God bless.