anyone tried an investigations agency to build an adultery case? or for missing person/s?

while I am away abroad)nagbago misis ko and nagtatago na after my child accidentally told me na meron na cia bagong daddy (nung tinanong ko cia kung sino daddy nia ngayon).. the child was in prep and does not understand kung ano nangyayari.. now tinatago na cia ng nanay nia .. resident na sa abroad ang misis at child ko but my wife decided na hindi na nia mag reside with me at yung bata eh dinamay nia .. after the nung huling usap namin ng bata it is likely na nasa adulterous relationship ang misis ko and I want to establish a case .. I would appreciate if someone could show me the right direction para ma reunite kami ng child ko...i always expressed sa misis ko na gusto ko mabuo kami for the sake of the child pero if she is bent to an adulterous relationship and i-deprive ako ng rights sa bata, i would take legal action.... sana may maka tulong/advice.. thanks in advance