SOPHIE SETTING JOE'S HASH WITH TELL-ALL PAGE-TURNER!

RUTHLESS Game of Thrones vixen Sophie Turner is planning a scandalous tell-all about her soon-to-be exhusband Joe Jonas - and the singer's former flame Taylor Swift is providing plenty of extra ammo, sources squeal.

- 

After the hitmaker filed to end their four year marriage, Taylor allowed Sophie, 27, and the estranged couple's daughters - Willa, 3, and Delphine, 1- to use her NYC apartment. The grownup gals have been spotted out on the town as insiders suggest they're planning Sophie's divorce strategy.

"They're spending lots of time together and have a ton of stories to share about Joe," dishes an insider. "It's kind of fun for them to let  it rip-outside of the kids' hearing range, of course."

The spy snitches the Bad Blood songbird, 33, still holds a grudge against the Jonas Brothers hunk, 34, for dumping her more than 15 years ago with a 27-second phone call!