If the five year old can't understand, then I think "Yes" is a completely decent answer to this question.

If I were in this situation, I would write letters to the child to be delivered/opened as they grew older. This way I would still continue to have an active effect on their life. We "exist" to other people when we have measurable effects on them, so this would be a way to continue to love them in a unidirectional way.