What is the ruling of religion and society on the wife returning to the husband's bond after she was divorced and married another, knowing that there are six children, and she regrets and repents?

You should have verified the information before rushing to divorce your wife when your family informed you of her departure, as the news might have been incorrect or she might have had an excuse. There is no harm in marrying her again; rather, it is good, as it reunites her with her children, especially since her situation has improved and she has repented, for "the one who repents from sin is like one who has no sin." Seek guidance from Allah through istikhara and complete your marriage to her, and do not pay attention to people's talk.