what if a 19 yr. old male born one month before the female and a 16 yr. old female have sex and they tell a pastor... does the pastor have to tell the police if it was told in confidentality?

Yes. According to the law outlined below, members of clergy are among those professionals who are required by law to report this to authorities. The mandatory reporting law includes Texas statute 21.11 "Indecency with a child" which is which essentially, is Texas's statutory rape law.

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261.101. PERSONS REQUIRED TO REPORT; TIME TO REPORT.

(a) A person having cause to believe that a child's
physical or mental health or welfare has been adversely affected by
abuse or neglect by any person shall immediately make a report as
provided by this subchapter.
(b) If a professional has cause to believe that a child has
been abused or neglected or may be abused or neglected, or that a
child is a victim of an offense under Section 21.11, Penal Code, and
the professional has cause to believe that the child has been abused
as defined by Section 261.001 or 261.401, the professional shall
make a report not later than the 48th hour after the hour the
professional first suspects that the child has been or may be abused
or neglected or is a victim of an offense under Section 21.11, Penal
Code. A professional may not delegate to or rely on another person
to make the report. In this subsection, "professional" means an
individual who is licensed or certified by the state or who is an
employee of a facility licensed, certified, or operated by the
state and who, in the normal course of official duties or duties for
which a license or certification is required, has direct contact
with children. The term includes teachers, nurses, doctors,
day-care employees, employees of a clinic or health care facility
that provides reproductive services, juvenile probation officers,
and juvenile detention or correctional officers.
(c) The requirement to report under this section applies
without exception to an individual whose personal communications
may otherwise be privileged, including an attorney, a member of the
clergy, a medical practitioner, a social worker, a mental health
professional, and an employee of a clinic or health care facility
that provides reproductive services.
(d) Unless waived in writing by the person making the
report, the identity of an individual making a report under this
chapter is confidential and may be disclosed only:
(1) as provided by Section 261.201; or
(2) to a law enforcement officer for the purposes of
conducting a criminal investigation of the report.