I'm so sorry you and your kids are going through this. It's so hard to know there has been cheating, but no clue on extent.
There is no way in the world I would move with her to another country without first having that poly. Even if you have to hop a little flight to do it.
My gut matches your gut on this one. More happened. She is trying to make you forget through a ton of sex. Technology is such that if you want to cheat, it's so easy. Trust once broken is so very hard to rebuild. It's almost like you suffer from PTSD...things are ok for a little while and then it hits you all over again what wsa done and bam, all the emotions come flooding back in full color.
Don't feel guilty ever about questioning her or doubting her. This only arose because she did something inappropriate (went on a date while a married woman and who knows how much more), and then continued a LDR with him, where they were so familiar with each other he called her 'baby'. GAG!!!!!
I would recommend not making any big life decisions (moving across the world) until you have the poly results or her parking lot confession.