Madam,
The answer is already given in my earlier replies. You have to sit calmly and read them thoroughly to get answers to your questions.
If your husband has received dasti notice, you need not worry any further. The court will give him one or two opportunities to present in the court and reply to your application seeking to set aside ex-parte divorce decree. If he does not appear, the court will take your application and hear your advocate and if the court is convinced that a fraud has been perpetrated by him in getting ex-parte divorce decree by obtaining signature from you on court notice mischevously, the divorce decree will be set aside. Again,he will be given opportunity to prove his contentions in the divorce petition to get divorce decree and you will be given full opportunity to contest the case.
Now, second question. After obtaining ex-parte divorce decree fradulently, if he married some other lady, what would be the fate of that marriage and that lady. If you prove that the ex-parte decree is obtained fradulently, the second marriage is void. Further, you will be entitled to prosecute him for bi-gamy.
I hope,I have clarified all your doubts. Every thing depends upon the contents of your application seeking to set aside exparte decree (how forcefully you put your submissions about his fradulent activity and how much your advocate could convince the court).
Wish you best of luck.