How can I atone for taking my mother-in-law's belongings from her apartment without revealing the secret, and the consequent ruin of my home, knowing that I regret it and have donated the belongings to an orphanage in her name?

We advise the questioner to overlook and forgive the entry of her husband's mother into her apartment and the use of her furniture. If the mother did not consume anything of legal value from the questioner's belongings, then it is not permissible for the questioner to take anything from her husband's mother's possessions. She must return what she took if it is still remaining, or its value if it is no longer remaining. Giving it away as charity is not sufficient as long as its owner is present and it can be returned to her.