Thank you for your question
My name is Clare
I shall do my best to help you but I need some further information first
Dies his girlfriend have any qualifications to be a tutor?
There is nothing wrong on the face of it with your ex's girlfriend helping your son - especially if she is indeed a teacher
Yes your ex should have consulted you - it would after all be much better if you could consolidate any work that she does - which you cannot do
if you are not told
However whilst he should have consulted you this is not a good enough reason to stop the tutoring.
You should offer to discuss matters with him using Family Mediation to try and resolve such issues and ensure that your son's needs are properly dealt with
I hope that this is of assistance - please ask if you need further details