i had the same situation when i was pregnant.
siguro 5 or 6 months pregnant ako nun.
Nararamdaman ko na something was wrong.
May officemate siya na girl na talagang pinaghihinalaan ko na.
So what i did, while he was sleeping, i texted the girl pretending to be him.
Take note, the girl was also in a relationship and with 3 children na!
So yun nga, i started asking how's her night. I think she was also making sure that it was him who's texting her so di siya masyado nagrereply until i texted her 'iloveyou' and she replied 'iloveyou too!'.
Ayun na, i started crying and inaway ko siya right there and then.
Umalis siya ng house that night and kinabukasan na siya yata dumating.
Tapos since then, kahit umuuwi lagi siya sa bahay, there were times na bigla akong iiyak tapos sasapakin ko siya while he's sleeping.
I almost broke up with him dahil di ko talaga siya pinatawad and i couldn't see na sincere siya sa paghingi ng sorry. Until i spoke to him and to his mom about it.
Then i gave him another chance. Pero sabi ko nga, di ko alam kung nagbago ba siya. Pero i know i changed. Kung dati i always track him down, ngayon di na. If he said kasama niya friends niya, e di ok. Basta ang alam ko, if it happens again, there wont be 2nd chance.
And my baby, surprisingly, is a very happy baby. Minsan naiisip ko ngang sabihin sa kanya na buti na lang happy baby ang baby namin at di naapektuhan ng infedelity niya. kaya lang pikon un e. hehe!