Welcome. Please go to the section Plan A and Plan B. You are going to be working very hard, even harder than you have been, because you want to save your marriage.
It's not fair what she's done to you, but you can save your marriage. You have to find out what her emotional needs are. She was lonely while you were gone, isolated, and not mature enough to cope on her own. She needed you. Yes, I know, you were working hard to pay the rent, the bills, buy the baby food, etc. She done you wrong.
Now she's interested in dating other men. She can't do that while she is married to you. FInd a good attorney, and go for custody of the baby. Get that in the works. Don't file for divorce yet; just work on keeping the baby safe from her silliness.
The recruiter screwed you. Your wife turned on you. And now you have to go the extra mile, just when you thought you couldn't keep going. Not fair. Life handed you a rotten hand.
Don't talk about divorce with your wife. Tell her you are standing for your marriage and that you are going to be a better husband and meet all her emotional needs. Take care of yourself, don't let yourself go to seed. No drinking, no sleeping when you have a day off because you are depressed, no cussing or swearing or raising your voice.
Can the base chaplain help you? Does your insurance cover marriage counseling? If so, try to see about having a session with the Harleys.
Wiser heads will be along soon to help you. Stay strong! And thank you for working in the service to protect our country. You are a good man for doing this.