Here are some excerpts from Swedenborg's "Arcana Coelestia" that help explain the inner meaning of this chapter:

AC 4811. The subject treated of in this chapter, in the internal Sense, is the Jewish Church and the genuine church; the Jewish Church is described by Judah, and the genuine church by Tamar.

AC 4812. The sons by Tamar signify the two essentials of the church, namely, faith and love--Perez faith, and Zerah love. Their birth represents that love is actually the firstborn of the church, and faith only apparently so.