Is it permissible to show the wife's chemise stained with blood from the wedding night to the family as proof of her virginity, and does this act fall under the prohibition of spreading what occurs between a man and a woman?

It is religiously forbidden for spouses to disclose the details of their intimate relations. The proof for this is the saying of the Prophet, peace and blessings be upon him: "Indeed, among the worst people in rank before Allah on the Day of Resurrection is a man who has relations with his wife and she with him, and then he divulges her secret."