そっちこそ、ギックリ腰で立てなくなってもおいて帰りますわよ。

、。

You're the one who'll throw out your back and be unable to stand, so I'll leave you here and go home.

Literal

Over-there [emph-こそ], throw-out-back [with-で] become-unable-to-stand [even-ても], leave-[and-て] will-go-home [polite-ますわよ].

そっちこそ '(you're) the one who should be X' is the reflecting comeback, where こそ marks the emphatic 'precisely / exactly.' ギックリ腰 'throwing out one's back' is a colloquial compound of ギックリ (a mimetic for a sudden sharp pain) + 腰 'lower back / hip.' おいて帰る is a compound: 置く 'to place / leave' + 帰る 'to return' = 'leave (someone/something) behind and go home.' ~わよ is the feminine emphatic ending.