Dude, it's over...you can never go back on this betrayal. She lied to you day after day after day, made you work like a dog in a job you hate, give up stuff you like doing (army) and made you a house slave all so she could bang her BFF husband!!!! She not only showed you massive disrespect and disloyalty, but she's showed what sort of person she really is...one who would cheat on both her husband and her best friend. She's shown you who she really is...believe her!!!!

Start gathering the evidence and getting your ducks in line for a divorce, it's going to happen. As much as you'd probably like to save this I doubt it can be saved. You will always be second guessing yourself and looking at her behaviour wondering if it will happen again.

IMHO you need to save yourself the heartache and finish this in as much of an amicable fashion as possible for your child.