I agree with the previous poster see if you are entitled to any benefits and apply to the court for SM.
I would also add that you could ask him why he is not paying you the amount any longer, if you are able to contact him. His circumstances may have changed, although you would have thought he would have told you beforehand rather than leaving you in this situation. Ha he lost his job etc?
Did you agree the payments would be for a certain length of time?
The only benefit I can get is reduced council tax because my income is a pension. He sent a message with daughter to say he wouldn''t pay anymore because she has gone to uni. I did not expect hiom to pay 600 anymore but at least something as she is at home 22 weeks a year and I will have to support her then. We had an agreement that until she finishes uni we would not sell house. We drew up our own agreement and both signed it but I am aware it does not hold any weight.
I saw solicitor last week to file for divorce and she said she would write to him and I beleive he has also seen a solicitor but not instihgated anything.
Go on the HMRC website working tax credits calculator with an income of £608 per month.
It said on the calculator you would be entitled to claim £1324 in tax credits from now to tax year end. So thats an extra £220 per month.Beter than a poke in the eye with a sharp one.
All the best