FB private messages used to file a case

Hi pa enlighten naman po ako, nagresign po ako immediately kasi gusto ko na po talagang maglipat ng bagong work kasi di na ko masya at gusto ko ng greener future. So I send RL immediately effective pro i know di valid un, kaya they tagged me as AWOL then after 1 week of absences kasi pumapasok n ko s new employer ko which naging client din nila dati for 2weeks lang. Naka 6mos n kong probationary sknila kaso hnggang s natapos un after 2 months pa sila naglabas ng panibagong agreement n regular na ko kaso di ko na yun pinirmahan kaya i decided n umalis nlng kasi 2 lng kming employee s isang office n un na andun we are working via emails lng. Tpos after a week, yung naiwan kong officemate dun naiwan nyang nakabukas yung facebook account nya tpos without her consent binuksan nila un at prinint nila lahat ng convo nmin na meron dun about s companya nmin pro ung involve kmi lang dalawa kasi private msgs nmin un s isat isa. Tapos un ung ginamit nilang proof as evidence para makafile ng case against us.. Is that valid?