Partner’s Ex won’t let him take his kids on holiday

I am the a mum to 3 kids whos father pays csa and has a new life we get on fine and all communication is delt with like adults. My fiancee however has a nightmare of an ex she still loves him and went mad because he had my name tattoed on him and we got engaged (they were apart for 2 yrs b4 we met) anyway since then she has stopped us having the girls every weekend, she wont let us take them on holiday, he pays 70 a week csa for them and has to go to his aunties to visit his boys who want to come stay everyweek. she sends vile messages to our mobiles including my sons and then tells everyone he never bothers!!!

She has never had a job in her life i have worked since i was 15 i am now 32 including when all my kids were babys and we have to now survive on his 120 wage after 70 has been taken out plus my wage and our tax credits we have weekly bills of over 300 pound and are always left with around 20 a week left!!! how are we supposed to pay for xmas and holidays even a camping holiday is out of our reach while that lazy cow has been abroad twice this year without the boys by the way and goes out on the piss everyweekend its a joke we just want to be able to provide for our family and tax credits dont take into account the loss of 70 a week and because were a couple we get punished if in was single i would be 200 a week better off!!!!