When Tom and Katie split, many Hollywood insiders were wondering why he didn’t immediately jet to Suri’s side. But as a close friend explains, it sadly wasn’t that simple. “He wanted to see her as fast as possible since this started,” the insider tells People magazine. “But he couldn’t shut down production of Oblivion and cost people their jobs. People count on him.”

When he arrived in New York 18 days after the divorce bombshell, it was clear that Suri, who leapt into his arms, was thrilled to see her beloved dad. But despite the joyous scene, there was still a clear sign of power struggle between Katie and Tom. On his very first day with his six-year-old, Tom found a way to send a strong message to his ex-wife by inviting his sister Cass – who was armed with stuffed toys for Suri – to their reunion. “Tom brought his sister with him for his first day with Suri because he knows that is the one thing that would hurt Katie,” a close friend of the actress tells Woman’s Day exclusively.

“Cass used to live with them in Beverly Hills until a few years ago and it was making Katie’s life a misery.” As People reports, during her marriage Katie was forced to spend a lot of time alone with Tom’s sisters while he was away on film sets. “She was like, ‘I’m living with your sisters and not you,” says the magazine’s source. Our insider adds that: “Katie broke down and told Tom she couldn’t take it anymore and that he had to choose which one of them he wanted to live with.”

At his then-wife’s request, he kicked his sister out of the Cruise compound and bought her a house nearby. But with Katie out of the picture, it appears Cass has been welcomed back into the fold – and into Suri’s life. And it’s the last thing Katie expected. Another source, who has met Cass four times, describes her as a “rabid” Scientologist and added, “She is an extremely intense person – and not somebody you would ever want to cross.”

Read the latest on Tom and Katie's split in this week's Woman’s Day on sale Monday July 23, 2012.