If you still want to go there with the investigating... try to get access to the cell phone account through the carrier, and you can go through the list of numbers that way. As far as sneaking around with apps and stuff like that. If you can try to go into the Google account search history and settings, if she has a laptop around the house, there should be a setting where you can get the password information for all logins if she cached them. You can even find hotel reservations if it's done electronically. Google links multiple devices like laptops and cell phones as well concerning emails, app usage, search history, passwords for apps, maps histories, place has been places, searched. There are also ways to Ping her device or her phone and get her locations in current real time. Just make sure you turn the notifications off on her phone because when you ping her a notification will come up that's Google device has been found and pinged. Find device app can do this.
Let me ask you something is going to really do you any good to know who it is? As long as you have a good idea and efficient amount of evidence that she's definitely cheating. As long as you know and develop patterns. That's really all you need to know. Trust all of us on this it's going to make you mentally and physically sick. Keep tabs on occasion and drop it for a while, otherwise it's going to consume you. You probably want to keep more of an eye on where she's moving, and if she's doing any legal research related to child support, child custody, divorce, mediation, etc. Put your heart and your relationship aside because it's dead. Stay 20 moves ahead on her in the legal game do your research have your consultations and keep tabs on where she is at with that. You have to protect you and your children first. Drop the rope and have some self-respect as an individual. You are not the one cheating she is. Your happiness your contention your values and your self-esteem does not come from your wife. Understand!? Try to balance your emotions bwtween yourself, who you right now, who you want to become, and who your W currently is. Be aware of this because it's very easy to lose your sense of self of Who You Are.
If you need any help assistance or technical tips send the questions I'll answer the best I can.
