Keep in mind, whatever you decide that lying about the length of separation is called perjury (lying to the court) and is a crime. NC law is one year and one day living separate and apart. The A of A, is going to go after the other woman only for alienating your husband, it has nothing to do with sex. The criminal conversation is going after your STBX. Adultery is illegal in NC so that’s where the “criminal” comes in. With this you have to show is proof of marriage at the time and that the act of adultery occured, which if she’s pregnant and it’s his child, shouldn’t be too difficult to do.
I wouldn’t agree to anything that is illegal, after all you have a daughter to think about. Your STBX will have to wait on his new life to start though the child will be born before your divorce is final.
Get an attorney, file for separation based on the date he moved out, including equitable distribution of any marital assets and debts, primary legal and physical custody of your daughter, and child support, and then in about 10 months or so, file for absolute divorce. Good luck