No, the appeal against the divorce order is not time barred, check section 28(4) of the Hindu Marriage Act, 1955 where time limit for filling appeal is 90 days not 30 days, and divorce was granted under this Act.
As far remarriage is concerned you can remarry any time after the decree of divorce but the period of filling appeal of 90 days should have been taken in account by you which you did not and remarried after 30 days.
The mistake of getting remarried after 30 days and not waiting for 90 days is due to wrong legal guidance of your lawyer, his inexperience and stupidity has caused this problem for you.
If the High Court set aside the decree of divorce, your second marriage will become null and void.
The maximum that High Court will do in such case is to ask you financially compensate your first wife by giving her good amount of alimony as settlement of the issue, allow the decree of divorce as granted by trail family court as valid so that you move ahead with your second marriage.