How can a woman stop complaining about her husband despite his difficult disposition and his insistence on wrong habits that are contrary to Islamic law, and what supplication can help her with that?

It is permissible for a woman to eat with her husband's brothers if there is no fear of temptation (fitna) and if there is someone present who negates prohibited seclusion (khalwa).

We advise you to fear Allah, repent to Him, and increase your remembrance of Allah and seeking His forgiveness. Among the answered supplications are the supplication of Dhul-Nun: "There is no god but You; glory be to You! Indeed, I was among the wrongdoers," and the supplication: "O Ever-Living, O Sustainer, by Your mercy I seek assistance; rectify all my affairs for me, and do not entrust me to myself for the blink of an eye," and the saying: "Allah is sufficient for us, and [He is] the best Disposer of affairs."

It must be known that there is no obedience to a created being in disobedience to the Creator. Therefore, it is not permissible to obey the husband if he commands something forbidden.