"what if the PA turned out to be true? What will you do then?"
There is a chance all his suspicions are true, and I think he needs to be prepared. As we have both seen here anything could happen, OM may cold call the house to get revenge for getting dumped, or his W may have a guilt attack and come clean. All possibilities. Jake are you ready to handle this?
Whether a PA/EA even happened she has betrayed his trust, the prepaid phone is a huge dishonest move infidelity or not. Jake needs to find out if he can get past this before any real DBing begins.
I can tell Jake is scared, most of us here have known this feeling. I just hope he can find the strength to keep moving forward no matter the outcome, (and we know it could be an ugly one).