He who speaks dispassionately of his brother's sin does so either to correct him or to benefit another. If he speaks for any other reason, either to the brother himself or to another person, he speaks to abuse him or ridicule him.
There are three things that move us to the good: natural tendencies, the holy Powers, good choice. The natural tendencies - as, for instance, when what we wish men would do for us, we likewise do for them; or, when we see someone in sore straits, we then naturally have pity. The holy Powers - as when moved to some fine deed, we experience their good assistance and prosper. Good choice - when, for example, discerning good from evil, we choose the good.
Someone may say: 'I have faith, and faith suffices for salvation.' St. James gives him the answer: 'Even the demons believe, and shudder. Faith without works is dead.' (James 2:17-19)
Remember that a good action is always either preceded or followed by temptations. God permits this so that the virtue, exercised in that particular action, may be confirmed, consolidated, steeled.
You ask for some way of completely eradicating irritability. The inclination to irritability is given us to use against sin, and we were never meant to use it against our fellow men. When we do, we act contrary to our true nature.
A man of good sense, realizing how beneficial are the judgments of God, thankfully endures the tribulations they bring him, holding none guilty but his own sins. But a foolish man, when he sins and is punished, regards as the culprit of his ills either God or men, not discerning the wisdom of Divine Providence.
When the intellect begins to advance in love for God, the demon of blasphemy starts to tempt it, suggesting thoughts such as no man but only the devil...could invent. He does this out of envy, so that the man of God, in his despair at thinking such thoughts, no longer dares to soar up to God in his accustomed prayer. But the demon does not further his own ends by this means. On the contrary, he makes us more steadfast. For through his attacks and our retaliation we grow more experienced and genuine in our love for God.
The one who engages in a pursuit of wisdom out of devotion and stands prepared against the invisible forces should pray that both the natural discernment (with its proportionate light) and the illuminating grace of the Spirit remain with him. The former trains the flesh in the acquisition of virtue through asceticism while the latter illuminates the mind to select the companionship of wisdom before all others, according to the Scripture, 'He works the destruction of the strongholds of evil & of every pretension which raises itself up against the knowledge of God' (2 Cor. 10:5).
Have great care of your children. We live at a time when much freedom is given to the expression of thought, but little care is taken that thoughts should be founded on truth. Teach them to love truth.
Our achievements must never loom large in our eyes; only our failures. But this must never lead us to despondency - the constant temptation - only to humility.
Do not lend your ear to the tongue of the slanderer, nor your tongue to the ear of him who likes malicious talk, speaking or listening with enjoyment to words against one's neighbor. Cut yourself off from them, lest you fall away from love of God and find yourself exiled from eternal life.
In answer to your question as to what constitutes a happy life, whether splendor, fame and wealth, or a quiet, peaceful, family life, I will say that I agree with the latter, but will add the following: A life lived in humility and with an irreproachable conscience brings peace, tranquility, and true happiness. But wealth, honor, glory and exalted position often serve as the cause of a multitude of sins, and such happiness is not one on which to rely.
He, in whose heart humility and meekness are reborn, will find true rest for his soul. He will be satisfied with everything, grateful for everything, peaceful and full of love for everybody. He will judge none and will feel no anger. His heart will be filled with divine sweetness, that is, he will feel in himself the Kingdom of God because God grants His grace only to the humble.