You should file an appeal against the decree of family court. However, the period of limitation for filing an appeal has lapsed. But you should take a plea for the condonation of delay in filing an appeal. If the court satisfied that there was a reasonable cause for delay then the court may condone the delay and admit your appeal.
You have solemnised marriage after the decree of divorce. After contracting the second marriage and birth of a child you are facing financial hardship to obey the decree in its letter and spirit. These facts were not present at the time of passing of decree.
So in the appeal you have to prove that in the changed circumstances the amount of alimony needs to be adjusted. The court can decrease the amount of maintenance if there is sufficient reason.
Lack of financial capacity of the husband itself constitutes sufficient ground for adjustment of permanent alimony. The court may lower the quantum of maintenance in its appellate jurisdiction.