Written statement is not required. The petitioner had already presented his case. If you want to rebut his case you need to present a written statement. As you don't have any intention to rebut his case, you will simply stand as a witness in court to confirm the allegations made by him and conveying to court that as conveyed in the petition you are in relationship with some other man, and your parents performed the marriage without your consent. But ... as you are after all the daughter of your parents you should take care to not land them up in trouble by saying that they forced you to marry they intended to defraud this boy by concealing facts about your relationships and all.
You will only say that societal pressure was heavy on my parents to get me married and they did not know anything about by I loved and so they thought my life would be better if an arranged marriage is performed. And they did not perform my marriage with an intention to defraud the boy. You see....try to understand these distinctions:
1. You are not the petitioner in this case. And the only possibility is that the petitioner be defrauded by your parents. There is no possibility that your parents forced him to marry you.
2. If you are the petitioner praying the court, then you would have pleaded that I am forced. As you are not the petitioner there is no need for you to plead or convey the court that I was forced by my parents.
Coming to the aspect of defrauding, to save your parents from criminal cases, admit the facts with little bit care by saying, "they were under pressure to discharge their burden and were facing pressure from society that is why they got me married to this man but they did not intend to cheat this man". And concealing a love affair is not at all a crime. If you were married with your boyfriend then concealment of such fact is a crime. If you are pregnant with him, then concealment of such fact is a crime. Not conveying stories of love affairs is not a crime.
Love affairs do happen ever since one become adolescents. Some are infatuations, some are passing affairs. No one can argue in a court saying A woman had not conveyed about 10 or 15 men that she had fallen in love since she attained age of sixteen to legally marry a man.