Trees, this may seem ridiculous, but bear with me. Despite all the horror since the discovery, I actually think the particular circumstances have actually protected you (and WH) from the full reality of it all. The pregnancy, your little one's arrival have given you something to focus on. In practical terms you have seen far more of each other that you would have if things had been different, and so far you continue to do so. It's enabled you to (sort of) continue with the family dynamic, and see his affair, and deceit as a minor, and done with aberration to be got over so that you can all get back to "normal".
The thing is, that's not going to happen. Even if he moves back tonight (and the spare room, won't help kid the DC by the way) you wont ever be back where you were before. I'm not saying you won't reconcile, or be happy again. But, it will be on a new, different, and hopefully better basis. This is not going to be possible if what happened isn't properly acknowledged, and dealt with by him. Or without out proper space apart both physically or mentally for you both. You've not had that yet .
Think back to how you felt initially, and at the second revelation. You'll feel like that again I expect, and you don't want to go through another change for you or the DC if you want him gone again, either short term, or permanently.
You don't have to decide either to have him back, or finish absolutely either today, or anytime soon. It is difficult for the DC. I think that one of the reasons for this is that they are only seeing their Dad sleeping away, whilst in many other ways you are still operating as a family unit. it's hard, but if you start to make more space, do things just you and them, and him and them it will be less confusing for them, although different. They don't need to stay over yet, but it shouldn't be a "sleep over". It should be spending time at their Dad's house.
Finally (thank God you say!), I am concerned how much pressure you are getting (directly or indirectly) from WH over this. I worry you are not reassure by him as you should be, and actually have concerns that if you don't publicly "reconcile" he might take up with OW? He might of course, but really that would say everything about him, and where he is. Again I hark back to his alterative life/friends. I remember at the start he was resistant to dropping them/it. Whilst you don't want to do his work for him, this is a no brainer. You do know that you are entitled to say right now to him , stop al of this, drop all of them and show me you have done it. And that this is a minimum requirement for me even considering us having any sort of future together. If I were you, I'd say this thing, and again it worries me that you seem anxious/unable to do so.
The more control you can take of your own situation, and whatever boundaries you need/want the better you'll feel. And your DC.