Is it possible to overcome doubts about a husband's past sexual orientation, especially given his current religious commitment and attempts to please his wife, and how can one deal with the hatred stemming from these doubts and restore normal marital life?

The default is to assume the best about a Muslim's affairs, so it is not permissible to harbor ill suspicions about your husband without evidence. What you did by attempting to insert your finger into his anus is a reprehensible act, and what resulted from it is not sufficient to indicate his perversion. You must combat these whispers and delusions and treat your husband well. Foreign films and smoking are forbidden, so advise him with kindness and be an aid to him in acts of obedience, and do not assist Satan against him.