my ex husband and i are divorced and have a court order in place where by the house is sold to pay my set fee of 50 k out of the house. he lives in it and pays the mortgage etc and i rent elsewhere with the kids and my partner. my ex took the mortgage of £729 and its on the market for £750k hence no interest in the house so an agreed 50k is to come to me from house sale and up to 6 months after date sold for any further money he may still owe to me up to that value from personal means. he owns a chill in wales etc and earns 90k per year. . the problem is, firstly he can't take my name of the mortgage as he not in the same financial situation as when we took out the mortgage so the house needed to be sold to give the court ordered clean break. problem is i have recently found out that he took the house off the mortgage 3 months go and has moved his girlfriend and her daughter into our home.!!! she has her own house and now rents it out so now pays towards our mortgage by paying my ex an amount each month like a shared rent almost!. he clearly has no intention of selling now as the location of the house is by his girlfriends work and her childs school and the fact is, he couldn't afford to buy a house anyway near the value or standard again which I'm sure his girlfriend doesn't know and he let slip they plan to develop OUR house to make an etc bedroom for her child. how can he do this when he owes me 50k and as long as he there, my name stuck on the huge joint mortgage and i can't move on and get out of renting and worried his girlfriend could obtain financial benefit to the house . plus wanting to move on himself and live with his girlfriend was his only incentive to sell and pay me out and release tie to me on mortgage but he has secretly just gone and moved her in and now i have nothing to make him sell it seriously even if courts made him put back on the market , he clearly will make viewings difficult etc as he wants to stay in it and develop it. what can i do?