Me and my husband divorced 6 years ago, our son is disabled, in the divorce it was written that he paid maintenance which he has and has him at the weekend, since our son has reached 18 he has stopped the maintenance and only will look after him one weekend in a month, my son is still at a special school until he is 19.

It will depend on the wording of the child custody agreement. Often for special needs children there will be arrangements made for long term arrangements. Have you discussed this with the lawyer that you used for the divorce and custody agreements

What state is this? Im thinking your meaning child support correct?

I live in the UK, my Ex done all the divorce and arrangements, but I can remember it saying that we will both have to think about long term arrangements for him. Is he able to just walk away like this and just have him one weekend a month?