The journalist 'liked' an Instagram post from her manager Sharon Finnigan, which read:
"It's funny how you're nice to my face. It's hilarious how you talk s**t behind my back. And it's downright comical that you think I'm unaware."
The iconic couple - who welcomed their second child at the end of last year - married in a lavish ceremony in Bowral in 2015.
The Daily Mail reported that the rugby league star is said to have ended the marriage just before Christmas.
Phoebe's activity on Instagram follows Joanna—who is the wife of Sam's brother, George— claimed Phoebe has "never joined the Burgess side of the family" for Christmas.
"You made a comment as though you had no care in the world for your sister-in-law," one angry Instagram follower commented on the post.
"It was the inability to show compassion and humility that caught the attention of your followers because however close you might be now with your husband and his family, another in very similar circumstances was suffering," they continued.
Joanna's most recent admission comes after she shared a photo of the annual Burgess family Christmas lunch, captioning the picture "was the best one yet."