fth, I understand that you are telling your H how you feel. I know that you are still hoping that you can somehow show your H that what he is doing is "wrong", that if you can just make him see that he is hurting his kids, you, the family, etc. than he will "see" that he is making a mistake and stop and come back. IT WON'T WORK. It doesn't matter if you are exactly right in what you say. He has a long way to go before he is even close to coming through his MLC. All you are doing when you say the things that you are is applying "pressure" on him. He will run from pressure every time.
As for him changing his mind about acting "like a family" when he comes home, going to birthday parties, etc. This is common. Now that he has told you that he wants a D and that he is leaving and that he has another W and you didn't just up and die or kill yourself or whatever, he is going to totally stop having any care about you or his old life. My W did the same thing. Once she told me what she wanted and the world didn't end or God didn't strike her down, she started no longer caring to keep up "appearances". He is relived that he is finally going to get to do what he wants and he is going to pull farther away now, not come closer.
When you talk to your H and say the things you did here, you aren't DBing, fth. In fact you are doing the opposite. I'm not putting you down for it at all. I did the same thing for a long time. But you have to stop doing this when you talk to him. This isn't the first talk you have had like this with him and if you look at it honestly, things are not only not any better, they are actually worse. You really need to stop and reread the DB basics. When you remind him how "wrong" he is, you are only driving him farther away. When you show him how he is hurting his kids, you are driving him farther away.
He is doing everything you say...he is putting himself before his kids, he is breaking his vows, he is doing all the bad things you say. But by telling him that is what he is doing you aren't helping anything. Your H is telling you this himself when he says he "..doesn't like talking to you because it hurts too much". He knows what he is doing is wrong and he doesn't like being reminded of this and will totally stop talking to you at all if it keeps going the same way.
I know how much you are hurting fth. I know you just want to say the right words and make your H see the light and turn around and come back to you and his family. There just aren't any words that can do this. Basics fth! Remember the basics.
You can and will get through this fth. I know it hurts, I know it isn't right or fair. But you need to start doing things that will help YOU get to where you need to be. The sooner you leave your H to work things out himself, the sooner YOU will start to move forward with your own life.