What is the solution to this suffering that afflicts me when supplicating and having a good opinion of Allah, which is represented by my fear that my supplication may not be answered or that it may be the opposite of what I prayed for, knowing that I see my righteous father supplicating for the guidance of my brother and he does not see a response, and I am a sinner and divorced?

Having a good opinion of Allah Almighty is one of the obligatory acts of obedience, and having a bad opinion of Him is one of the great sins and a characteristic of polytheists and hypocrites. Rushing for the supplication to be answered is one of the afflictions of Satan that the Prophet, peace and blessings be upon him, warned against. A supplication may be delayed for a wisdom known to Allah, or it may be answered by averting evil or by storing up reward instead of fulfilling the exact request, as he, peace and blessings be upon him, said: "No Muslim supplicates with a supplication in which there is no sin or cutting off of kinship ties, but Allah will give him one of three things: either He will hasten his supplication for him, or He will store it up for him in the Hereafter, or He will avert from him an evil equivalent to it." What you fear regarding the non-response to supplication is from the whispers of Satan, so you must repent to Allah from sins.