He had the cheek to ask his ex-girlfriend to babysit for them.

他竟厚着脸皮要他以前的女朋友为他们临时照看小孩。

《牛津词典》

Maybe an ex-girlfriend or wife?

也许是前女友或妻子？

youdao

It reminds me of my ex-girlfriend.

那会让我想起我的前女友。

youdao

For those of you who are on the run from the FBI, your Visa has run out, or you're sitting next to your ex-girlfriend, now would be a good time to put a paper bag over your head.

被FBI通缉的,签证失效的,还有前女友就坐在旁边的,赶快找个纸袋子把脸给蒙上

耶鲁公开课 - 博弈论课程节选

Nor were the allegations supported by any evidence other than the word of the ex-girlfriend.

WSJ: Judith Grossman: A Mother, a Feminist, Aghast

His assets were recently frozen during a dispute with his ex-girlfriend following their split.

FORBES: Russian Tycoon Boris Berezovsky's Death 'Consistent With Hanging', Say Police

Capello sacked John Terry as England captain over allegations of an affair with Wayne Bridge's ex-girlfriend.

BBC: Fabio Capello warns England squad over conduct