When people are away from Allah’s law and religion, their life becomes
unbearable. It is not your right to ask about his past. You are not allowed to speak to your brother in law nor mix with him.
If your husband repented sincerely, and he is a good man and takes good care of you , ignore his past as both of you were sinful for disclosing previous sins which Allah has concealed.
Do your best to make him love you more than any other woman.