Generally people (even friends and family) don't ever really find peace with it, it's not even easy for people to support someone who's dieing if they want control over when they die. It's just kind of what happens a lot. Granted there's also frequently not much you can do about it either. Doesn't help people who just can't go on anymore.
It's one reason why many (most likely) don't tell family--we know they'd just try to stop us, or get us committed to a psych ward, or counseling, medicated (more so than we may be already).
Why do you think that all you're doing is failing?
I have a thing where if a person has doubts, hesitations, it's normally good to try and resolve them first. You may find the ctb option might not be needed anymore, or maybe it will just confirm it. Really it all comes down to what you want, and what you want to do. I mention this only as you said you didn't know what to do, so I took that to mean you have questions, or some doubts. Which is fine too.