I would continue to attempt to contact CO to make sure his fellow officer got him the message. Ensure that he has all the information he needs.
I'm sure Allan A has described information which is going to be useful for you, but just for my thoughts what is going to be useful:
1. Phone records 2. Copies of text messages 3. Copies of emails 4. Contraceptive devices 5. Audio recordings 6. Video or images sent between them 7. Key to apt, clothing articles 8. Testimony from fellow soldiers or civilians confirming the affair 9. Hotel reciepts
Also like I tell anyone being cheated on, take care of your physical health, this would include diet and excercise. Also you may want to take up a martial art class and take it seriously, one that is going to help you in a street fight.
