people are mean in divorces regardless of the reason behind the D. They also lie about the M to make it seem not so bad to be ending things.
You need to accept that it was an affair. It was not an EA before he moved out, it was a PA. You didn't catch it because you weren't looking and they hid it. That's what people in As do - lie and hide. He moved out. This means he was planning his move if he already had a place to go. 3 days later she moves in with him. Do you really think she decided, in less than 3 days, to leave her LTBF and move in with YOUR husband? Who on earth, except someone in an A with the person, would feel even kind of alright moving in with a friend's husband when the friend just up and left without warning not 3 days before. They are in an affair. They were in one before he left. They were in one when he started discussing being unhappy. They were in one the day he left. They were in one the day she left, and they are in one now. Do not spend another second wondering about this. If he tells you again that it isn't, just remind him you aren't an idiot, and if he's going to continue to lie to you you'll make his life a living hell.
I also assume she ceased being your friend the second she moved in with him. Why would that be? I bet you thought she was your friend more than his, right? And yet she moves in with him and drops you? Come on, stop hoping this is a bad dream. Your H is fucking her. Your H was fucking her when he lived with you. I'm sorry - I know that hurts but you need to wake up and realize that what you hope isn't happening is happening. They are cuddling, they are sexting, they are fucking, they are making plans, they planned to live together when he still lived with you and she came over every day. They tell each other they love each other. They spend every free second together. This is an affair. Your H cheated on you. He is living with OW. He is hiding it to do better in the D.
Please, stop talking to him. You said he came over to fix a pipe. No more of that! Call a plumber and send him a bill for half of it. You have nothing to say to him, and he will do nothing but lie. As long as he knows he can come home to you, he doesn't need to miss you. You have to make yourself scarce to him. You have to make him see that you are GONE - that he's blown it. He will NEVER come back otherwise. He may never come back now. And so what? Will you ever trust him again? Will you ever believe he loves you? Will you ever feel safe? He's showing you what a weak coward he is. Why on earth do you want him?
A lot of what you feel is the pain of rejection. He's 'chosen' another. You want to be #1, and who doesn't with their spouse. But him? Please, he's a cheater, a liar, a coward, and cruel. You can do much better than that. Let the skanky OW have him. She's as gross as he is, sneaking around, lying, sleeping with someone's husband. Just gross.
Please, stop texting, calling speaking to him. And get all of the evidence you can. He's military, so in a D you will want proof of his A. Do whatever you need to do - bug his car, hire a PI, whatever, but prove this A he's having. Then you can let him know that you'll be keeping the farm, he'll be paying his half of the mortgage until you can refinance on your own, and he will not bother you, at all. If he does, you'll fight the divorce. You'll go after his pension from the military. You'll out him to his superiors with the PROOF of the A and request a court marshalling.
You don't need him. He's a pile of dog shit that is a cheating lying whore. What do you need him for?
You know he's lying about the marriage and his feelings. You were there. You've been around people that don't like you before. We all have. You catch little looks out of the corner of their eye. You hear in their voice contempt. You see them actively finding ways to avoid you. He didn't have any of those signs. Why? Because it isn't true. It's his bullshit excuse to make himself NOT the bad guy. He's a cheater, and he's the bad guy.
Get that proof, and do NOT let him walk all over you. Do NOT want him around. Do NOT contact him again, for anything beyond dictating the terms of your separation. If he fights you, go after him, hard. Let him know of your plans and that his actions will dictate how you handle this divorce, but make no mistake, it will be on YOUR terms.
Be strong. You don't need him. No one does. He's brought you misery. Be thankful he's not living there. Be thankful he left before kids were in the picture. Be thankful he's screwed up so badly that you can tell him that you will go after him with every breath in your body if he continues to lie and make this about you and your issues. This is NOTHING but his issues, his weaknesses, his lying, his whore.
Don't put up with him. You're a lot better than he is, so start acting like it.