Indeed, at the trial of a divorce suit, especially at a peace hearing, both husband and wife must come in person. Although both may represent to their proxy, but for the purposes of the examination, the judge may order both to present themselves. Is the divorce workable without your presence / consent? If what you mean is that you (as a defendant) did not come at all and also do not represent at all to the power of attorney, then the judge can pass the verdict of verstek.
Regarding the legal status of the child of your husband and his lover, there are at least two possibilities that can happen that is your husband’s lover gave birth before marriage or after marriage:
The first possibility, if the concerned child gave birth before marriage, then legally, children born outside marriage have a civil relationship with his mother and his mother’s family and with men as his father who can be proven on the basis of science and technology and / or other evidence according to the law has blood relations, including civil relationships with his father’s family.
The second possibility is pregnant mating. By law, a pregnant woman out of wedlock, can be mated to the man who impregnated her. Marriage with the pregnant woman can be performed without waiting for the birth of her child. With the marriage being held at the time of the pregnant woman, there is no need for marriage after the child is born. The child born of the marriage status is the legitimate child of both.
If Defendant Not Attending the Separation Trial Process
In principle, in the process of divorce sessions in force in Indonesia, both parties (husbands and wives) must be present at the hearing in order to make peace efforts between them. This matter has been arranged in Article 130 paragraph (1) Herzien Inlandsch Reglement (HIR) jo. Article 31 of Government Regulation Number 9 Year 1975 concerning Implementation of Law Number 1 Year 1974 regarding Marriage (“PP 9/1975”).
However, a spouse or husband is permitted to be absent from the divorce proceedings by authorizing the other party to represent the person in the divorce trial. 
However, if you are Muslim, the provisions of the ceremony will be based on Law Number 7 of 1989 on Religious Courts (“Law 7/1989”) as amended by Act Number 3 of 2006 (“Law 3/2006”) and amended the second time by Law Number 50 Year 2009 (“Law 50/2009”).
Article 82 paragraph (1) and (2) of Law 7/1989 regulate:
(1) At the first hearing of a divorce suit, the Judge tries to reconcile the parties.
(2) In such peace proceedings, the husband and wife shall come personally, except where one of the parties residing abroad, and unable to come personally, may be represented by its special authorized power.
(3) If both parties reside abroad, then the plaintiff at the peace hearing must face personally.
(4) As long as the case has not been decided, a conciliatory effort can be made at each hearing.
In relation to the presence of a spouse in court, Article 142 Paragraph (2) of Presidential Instruction No. 1 of 1991 on the Propagation of the Compilation of Islamic Law (“KHI”) is also mentioned that in the case of a husband and wife representing to his / her proxy, for the purposes of examination, the Judge may order concerned to present itself.
So, we can know that indeed in the trial of divorce suits, especially in peace hearings, both husband and wife must come in person. Although both may represent to their proxy, but for the purposes of the examination, the judge may order both to present themselves.
Is the divorce workable without your presence / consent? If what you mean is (as a defendant) does not arrive at all and also does not represent at all to his / her proxy, then under Article 125 HIR the judge may issue a verdict of verstek.
Verstek’s verdict is a verdict imposed if a defendant is absent or not represents his / her power to face even if he or she has been properly summoned. If the defendant did not file a verzet (verdict) verdict against the verdict of the verstek, then the ruling shall be deemed a permanent legal ruling. A further explanation of this verdict can be found in the Verstek Decision and Court Bond Article.