Then ask the court to order your spouse to pay. If you have children, you should consult a lawyer. Well, the lawyer tells you about parental rights and responsibilities. For example, in Connecticut parents have a duty to support children until the age of 19 or until they graduate from high school, which ever first occurs. I thought children were supported until they turned 18.
Every state has a set of child support guidelines.
Then there shouldn't be any surprises. Ideally, but lawyers still come up with arguments persuading the courts to deviate from the guidelines. Also each state has a different set of guidelines. Tell me how much income you have, including interest and dividends. I also need to know your spouse's income, and the cost of child care and family medical insurance.