Brian Cashman’s former mistress threw a curveball in the escalating A-Rod steroid scandal yesterday — insisting the slugger’s lawyer drop his star client because the Yankee GM spilled secrets to her about steroid use among the Bombers and that created a conflict of interest.

Louise Meanwell who also uses the last name Neathway is charged with trying to extort Cashman during their 2011 affair.

In court papers filed in Manhattan Meanwell demanded lawyer Joe Tacopina drop A-Rod because one of Tacopina’s partners Stephen Turano is representing Meanwell since last year in a separate case in New Jersey.

Meanwell says she gave Turano “intimate details” of her relationship with Cashman and their conversations and claimed the GM told her he knew about Yankee players’ steroid use.

but had a “win at any cost attitude” and was “ambivalent’’ to drug use “so long as nothing came back to the Yankee organization.”