Bluntly, what is there to talk about? The sole responsibility of where you all find yourself lies with him. He has the thinking, the dealing with, the explaining to do. First of all to himself, and then you. It's up to you whether you want to listen, move forward whatever.
He is still seeing you as a unit (and so are you I think, it's scary not to), and that you can sort this together. You can't. You may be able to rebuild a new relationship, but at this stage he needs to put the work in. And to be blunt again, he's not. I am not sure he has even admitted yet to the full extent of the deception. Not to mention the ongoing contact with the "friend" which in itself will chip away at you, and your relationship.
Space is vital here, and I know it is hard. Try to see you and DC as a unit as much as you can, and ask what is best for you all at this point. You really can't think clearly with him hovering around talking about talking all the time. You could suggest only hand overs, baby time and talk only about DC arrangements, nothing else for a month, or whatever. And keep to it. You have enough going on, all of this must be exhausting you. Give yourself a break. It will also mean that he has to actually face what he has done, what is happening without your support and actually deal with it alone. I realise this might be outside what has been the relationship dynamic, but that is gone now remember. He has seen to that