Am I going to owe child support for the rest of my life?

No. Child support typically ceases when the child reaches the age of majority (18 in most states, in others it may be 21), or when the child becomes emancipated by marriage or joining the military or armed forces. In some cases child support is paid until the child finishes college. This type of support is called "after-majority educational support," and is usually case-specific and is achieved by including a specific clause within the separation agreement.

Be aware, if the child is 18 and is still a full-time high school student, child support can be extended until the child graduates from high school, or turns 19.