I think CW actually capitalized on the estrangement resulting from nutgate. That way he could tell the Watts clan and his best friend how he had finally seen the 'shady' side of Shanann and was divorcing her, while keeping Shanann, her family and her friends in the dark.
No doubt Ma Watts was thrilled about her boy leaving his pregnant wife and little girls. It must have been hard for her to keep the joyful news about the divorce and her son's affair to herself.
Interestingly, CW penned a letter on 8/6/18 and gave it to his sister: "If anyone gets this letter, I would never do anything to hurt myself, my children or my wife. If anything happens to me, please investigate my wife." This was same day he also told his best friend (Jamieson) that he was done with Shanann. So IMO, this proves he had decided to murder his family at least one week beforehand. He planned for his own family and friends to back up his story about how his 'spiteful' wife took his 'beloved' daughters from him, never to be seen again.
MOO
discovery page 728
CHRIS then told JAMIESON in text messages that he had seen the true side of SHANANN and was done with her, and didn’t want to be with her anymore.