The point of lying?

[KellBell0820]

I have a thread in newcomers and have been posting there mainly for about a month now. But I need some more specific advice so I decided to make a thread here.

The basics are Me: 24, H: 26, D: 3, 2 SS: 7 and 5.

He deployed last July, was gone for a year. I'll never say I was wife of the year, but I wasn't a bad wife either. While he was gone I was often scared (his job was to find and blow up IED's) and as a result wasn't always "there". We talked all the time, but he felt I wasn't I really there is what I mean. In May he started throwing around a possible divorce, we went back and forth and when he came home in July I told him it wasn't what I wanted and he told me his mind was made up. When he came home on leave at the beginning of August he filed D papers without telling me in Arkansas (I live in Tennessee).

He spent his entire leave basically avoiding me and D, left on my birthday to go back to NY (where he's stationed). At the end of August I got confirmation on OW via text messages I found from him about her (a birthday dinner he paid for, him staying with her, etc). I confronted him but felt like I didn't really have enough info so it was mainly about his lies to me. Over the next few weeks I found out more, like that OW is now living in NY with him via a mutual facebook friend. I've been trying to stay dark and NC, but today it kind of blew up. He called and the conversation turned from D and him re-deploying next fall to OW. He told me he had no idea what I was talking about and I asked him to give me proof that there wasn't OW, I wound up with his facebook login info. Of course when I logged in all of his messages were gone, but I know who the OW is so I went to her facebook page. I found things that indicated she was living with him in NY which leads me to believe they've been "talking" and "dating" for longer than the 4 months we've been "separated" and definitely longer than the 2 he's been home. There were pictures of our kids, some photoshopped with cute little phrases like "our princess, our (D's name)" . .

I confronted him about my findings and he's still telling me he has no idea what I'm looking at, there's nothing showing he's having an affair (or had one), there's no OW, and I'm crazy. He's also been diagonosed with a TBI (traumatic brain injury) and there's a very good possiblity he has PTSD as well. What I don't understand is why, if he's already filed D papers and has no intention of sticking around, why is he still lying? Why would it matter if I believe him or not? What steps do I take from here? I can do NC regardless of our D (he's only called once to talk to her in the past 3 weeks), because I'm definitely not ready to talk to him anymore right now.