。
If we stop now, all our efforts will have been for nothing!
Literal
Here [at-で] interrupted-[conditional-たら] original [gen-の] Mokua-mi [copula-だ] [emph-ぞっ].
元の木阿弥 (もとのもくあみ) is a proverb/idiom meaning 'back to square one / all for nothing,' derived from a historical anecdote about a monk named Mokua-mi who returned to his original lowly status. ~たら sets up the hypothetical. The emphatic ぞっ (with the small っ indicating sharp cutoff) expresses urgent masculine warning.