If, in the scenario you mentioned in your OP, we had "a break" it would depend on whether it was a real "time apart to be single people" break, or "time to think". My DH sleeping around would be hard to get over, and the baby would simply be a constant reminder of that betrayal... it would make forgiveness very hard for me.
Even if this baby was a child that was conceived before our relationship that he only became aware of after the marriage, I couldn't help but struggle. It would be a complete change of "our life" together and it would undoubtedly cause some angry and bitterness. Really depends on the mother of the child too. Whether she's reasonable or difficult to work with.
I think a lot of your (understandable) anger and hurt comes from not even getting a chance to deal with it yourselves before the OW was involving friends and family. You were/are embarrassed and she's airing all this dirty laundry.
So, I think you need to compartmentalize this. Give yourself the time to adjust to this development. Don't rush your relationship with your husband. This baby coming will change things, for you, for your children, for your husband. He also needs this time to process how he feels and not do or say something that will cause more sadness and regret for him (like ignoring the child, alienating his wife, alienating his children). It's okay for him to be happy when he sees the baby (if it's his of course). He will feel guilt, he will start keeping secrets and not telling you about his feelings towards the baby if he thinks it will upset you.
TL:DR Take a step back. Reassess once the dust has settled.