Madonna's son quit her tour after she confiscated his mobile phone.
Rocco Ritchie was "pushed over the edge" by his strict mother's belief the device was interfering with his homework, so following a row over its usage he quit life on the road with her to go to London to stay with his father Guy Ritchie and stepmother Jacqui Ainsley a month ago.
A source told the Daily Mirror newspaper: "Madonna is quite firm with Rocco and she took his phone from him when it interfered with his studies.
"She is stricter than Guy and Rocco doesn't like it. When she took the phone away, it pushed him over the edge."
The 57-year-old singer went to court in a bid to have Rocco return to her in New York for Christmas but he defied the order to stay in the UK.
And 'Man From U.N.C.L.E.' director Guy is now said to have hired lawyers as he prepares to battle to retain custody of the teenager.
According to reports, Rocco - and his father - feel he has a more "stable and loving" home life with Guy, his wife and their three children, Rafael, four, Rivka, three, and Levi, 18 months.
The teenager thinks his 'Like a Virgin' singer mother is "too controlling" and doesn't pay him any real attention.