I am the resident parent and my ex now has changed her mind, what rights do i have?

Hello everybody i hope you can help. I am the father of a beautiful 10 year old girl. I have always maintained a good relationship with her and up until recently was on ok terms with her mum. Originally my daughter lived in the UK with her mum until she was 8 years old. At the age of 8 my daughter and her relationship with mum broke down to such a point where mum begged ( and i mean actually begged) for my daughter to live with me, the main reason being her new boyfriend and my 8 years old (at the time) hated each other and Ex was leaving her with babysitters/childminders/friends so she could enjoy time with boyf!. In addition to that she was, be her own admission being bullied relentlessly by her sister to the point where she would stamp on her chest in bed, report it to her mum and be told off for telling tales!!1

I live in Abu Dhabi and i have been led down the garden path my ex before so i made the following stipulations; My daughter comes to live with me permanently in UAE, it is decided by a court, Ex agrees in court that this is in my daughters best interests. In July 2015 a high court judge wrote an order saying the following: It is ordered by consent that XX(daughter), will leave the jurisdiction of the Uk to reside permanently with Dad in the UAE.
In the notes it says that we can review the situation at the 2 year point as that is when daughter is due to attend senior school and a change of home(if any) should take place then as it would disrupt any schooling etc.
So fast forward to 2 years later or now, Ex is demanding that as she is now split from her boyf it is up to her that she gets her daughter back to live with her. My daughter has told her she loves living with me and my wife and our 2 year old son, loves the UAE and the schooling and doesnt want to come back. Ex is insisting i am putting these words into my daughters mouth and that legally she AGREED my daughter was going to be returned....phewww this is taking long sorry!! Additionally, my Ex has said she is refusing to pay Child Support as i live outside the UK, i have reminded her that it is the morally right thing to do and that in the 6 years we were apart i never once missed a payment no matter where i lived in the world.

My questions are as follows:

what is my legal position
what is the worst case scenario
How do i prove my daughter is happy here and the situation that led to the breakdown in the relationship has not gone away

I am about to ask my solicitor about what power the child contact order has in relation to this and what my Ex could do to supersede it. But any help on her would be very gratefully received.

thanks in advance