to the bitter end
until something is finished

[TahlilGaran] Advanced Learner's Dictionary ▲

to the bitter end
if you do something to the bitter end, you continue it until it is finished, although it is difficult and takes a long time.
Many climbers gave up before they reached the summit, but I was determined to stick it out to the bitter end.

[TahlilGaran] English Idioms Dictionary ▲

to the bitter end
to the very end
We stayed to the bitter end and watched our team lose very badly to the other team.

[TahlilGaran] English Idioms Dictionary ▲

to the bitter end
adv. phr. To the point of completion or conclusion.
■ Used especially of a very painful or unpleasant task or experience.
Although Mrs. Smith was bored by the lecture, she stayed to the bitter end.
They knew the war would be lost, but the men fought to the bitter end.

[TahlilGaran] English Idioms Dictionary ▲