Do child maintenance payments cease if I marry or enter into a new relationship?
No. Your ex be it spouse or partner has a legal obligation to continue making payments for the benefit of the children, given they are the absent parent. Your relationship status has no bearing on these payments as they are purely for the benefit of the child or children.
For more information, as to when child maintenance repayments usually cease please visit https://www.gov.uk/when-child-maintenance-payments-stop.