Pregnancy does not "halt" a divorce, although, depending on the judge before whom the case is pending, the divorce might be delayed and the entire divorce case will definitely take longer.
From the facts given, there are many things that could have delayed the divorce -- not the least of which is the husband's military deployment. If he is the one who filed for divorce, then his deployment might (but does not automatically) delay the divorce.
But you ask many other questions too -- and it's a confusing array.
First, if there are allegations that child born during a marriage is not the child of the husband and the wife, then the court must determine whether it is in the child's best interests to order genetic testing to determine if that is the case. The court must appoint an attorney to represent the child's interests (a 'guardian ad litem'), who investigates and represents the child--not either parent. That attorney then advocates to the court for what the advocate believes is in the child's best interests (first, whether or not genetic testing is in the child's interests and second whether the child should be determined to be not a child of the marriage). Since there are alleged to be two children not of the marriage, there may need to be two separate attorneys appointed.
Second, divorce is not a "fault" based proceeding. And the mere fact that a married person has a child with a person not his or her spouse means very little -- other than that the parentage needs to be determined. The court cannot "punish" a parent for an extramarital affair. The court is bound to determine what is in the best interests of the individual child, rather than to punish a parent (and possibly a child) by awarding a child to the "innocent" spouse because of that extramarital relationship.
Third, just because a divorce is "halted" doesn't mean it is "dismissed." The divorce may be "stayed," it may be sitting waiting for action by one party or another, or it may have been dismissed because of the failure by either party to do anything for a substantial time (depending on the judge and the district). And as long as the divorce continues on file in Kansas, Kansas is the appropriate place to continue with that divorce action. Merely because one (or both) parties are not now living in Kansas does not mean Kansas "lost" the power to enter a divorce; it didn't.
Fourth, it's unclear what you mean by "his mom is willing to come down and live in Texas with him where he resides...." Child custody matters are between parents and the court determines what time the parents should have with their children depending on their availability to care for the child among many, many other considerations.
Fifth, you mention that Wife now lives in Atlanta (Georgia) and Husband now lives in Texas. Again, however, if the divorce is still on file in Kansas, then the divorce can proceed in Kansas. Husband also can dismiss the case; but that doesn't mean that it would appropriately be heard in Texas -- since Wife doesn't live there. Dismissing the case in Kansas might create a jurisdictional nightmare on many different issues. But there isn't anyway to know the details unless Husband (and/or wife) consult an attorney who is knowledgable about the jurisdictional issues involved.
Sixth, it's also unclear the time periods you are talking about. Time matters. And where a child is born also matters -- again, because of various jurisdictional limitations on the courts.
Because of all these issues, your friend needs to talk with a competent lawyer who can advise him about all these -- and many other -- issues.
This response does not constitute legal advice and does not create an attorney-client relationship. I am licensed to practice only in Kansas. Seek legal advice from an attorney in your state or the state in which your legal claim exists.