Hey there, fellow service member here. Get your finances squared away ASAP. Take whatever you can and sequester it in a personal account. Collect any and all evidence of her infidelity. Do not succumb to rage or anything dumb because 9/10 times it’s your word against hers and that won’t end well for you. Go talk to legal, make sure everything you have is super tight and then serve her with divorce paperwork. She is a cheater and will not change. Do not get caught in the trap of trying to change her, she won’t. Finally, and this is important, talk to your first Sgt and make sure your work knows what’s happening, if she’s crazy she might seek revenge by calling your command and accusing you of cheating or any number of things that could ruin your career. Be precise and focus on getting things square and you will be fine.