Holy Gospel of Jesus Christ
Saint Matthew 5,38-42

 «Give to the one who asks of you, and do not turn your back on one who wants to borrow.»

The ancient Jewish criminal law 'an eye for an eye and a tooth for a tooth' very hard, merciless, even punished the murder of a member of a family with the killing of a member of the other to which the murderer belonged, even if in reality it seems that it was possible to replace the punishment with a monetary compensation that the guilty party had to provide to the victim.
Jesus is speaking here to His disciples, Jews educated in the observance of a steely and very complex law, full of prescriptions and meticulous behavioral precepts; in ancient times among the Jews there was no place to examine a crime to establish whether the offense was intentional or not, whether the action was justifiable, or had mitigating circumstances. There was only the fact that had happened and its restitution, repaying the guilty party with the same coin.
Jesus changes this point of view, and in this sense we can say that He establishes a new law, which rejects violence as an end in itself, and introduces that of love and consideration of the rights of others.

« When someone strikes you on (your) right cheek
turn the other one to him as well ... »

Jesus speaks to the disciples and, knowing them well, he makes use of hyperboles and parables, so that they may fully understand without ambiguity what he wants to say.

Love in the community life
First of all, referring to a community such as that of the disciples or of the first Christians - those described in the acts of the apostles - such a close communion of persons (Jesus is no longer physically present there, and cannot be seen in person) in the long run can cause some negative feelings, and arouse aversion among some members.
Practically in these cases, the shield against violence, spites or even the evil actions that some can do to others is to act with one's heart, that is, to show love for the brother, to forgive and renounce to oneself in favor of others. This is a constant and insisted theme throughout the Gospels

«But I say to you, offer no resistance to one who is evil; When someone strikes you on (your) right cheek, turn the other one to him as well;»

With the acceptance of the received evil, and the renunciation of oneself for love of the other, it is the heart that in the end wins.

In one's life within a family
Even in a natural family, where there are emotional and blood ties that therefore should be deeper and more solid, negative situations can occur, especially when it comes to matters of interest and not only that.
Even in families, therefore, situations similar to those of larger communities must be considered.
Indeed, certain extreme situations of one or more of the members of a family, such as madness or drug use, may even be less easily dealt with than in a larger community.
In today's society, real charitable associations are swarming, but also pseudo-such ones, which mainly carry out meritorious work, sometimes indispensable towards the whole society. But unfortunately widespread hedonism, practical atheism and materialism play their negative action everywhere in trying to destroy the natural family, which instead is the foundation and the engine of a healthy civil society.

In relations with one's neighbor in civil life
Since in other passages of the Gospel, I read that self-defense of possessions and family against external threats is described as normal, I think I know what Jesus wants to tell me in this passage.
Of course I don't think He really wants to tell me that, even if I can offer valid resistance, I should resign myself and passively lend myself to the abuse of any violent person who meets you on the street, just as it is not logical that a society should not organize itself to defend against external and interior enemies.

In conclusion
WHAT JESUS ​​ASKS ME TO APPLY IS COMMON SENSE IN TRYING TO TREAT MY NEIGHBOR AS I WOULD LIKE TO BE TREATED MYSELF IN ANALOGUE SITUATION.
IT IS NOT EASY, ESPECIALLY WHEN IT IS CLEAR THAT WHO IS IN FRONT OF YOU IS INTERESTED IN THE LYING, IS IN BAD FAITH OR IS IGNORANT OR SIMPLY A STOLID, CONSTITUTIONALLY UNABLE TO ACCEPT OTHERS AND THEIR IDEAS, OR STRETCHES TO CHEAT.
With people like that it seems useless to talk, but charity would dictate not to give up and persevere.
WHERE IN CRITICAL CASES THE CIRCUMSTANCE IN WHICH THE LEGITIMATE DEFENSE IS NOT APPLICABLE, YOU SHOULD HAVE THE PATIENCE TO RESIST, NOT TO AGGRESS AND NOT TO INSULT THE NEIGHBOR, OR WORSE, EVEN IF IT WOULD DESERVE IT
It is important to avoid returning any slap, physical or even and above all of a moral nature that is - a case that most frequently occurs - trying to reciprocate with kindness and humor by giving up one's pride.
I who write here, many times I havn't been able, and I ask always Jesus to give me the courage and the intellect when needed for such an act of love.

WHEN I THINK THAT SOMETHING GOOD I WOULD LIKE TO ACHIEVE, IS IMPOSSIBLE OR DIFFICULT, PRAYER IS THE MOST EFFECTIVE WEAPON TO USE, EVEN WHEN I THINK IT IS NOT USEFUL, OR WHEN EVEN HAVING NOTHING TO PRAY FOR.

LET'S ALWAYS PRAY, CONSTANTLY AND WITHOUT TIRING EVER ....

END OF COMMENT

HISTORICAL NOTE OF THE PERIOD:

• As can be seen from the Gospel and from the reading of the acts of the apostles and the letters of St. Paul (a Roman citizen), while the so-called law of retaliation is in force, or the custom of stoning sinners, blasphemers, and adulterers, Jews are not allowed put anyone to death without first the sinner being tried and judged by the Roman Procurator, if he is present in the praetoral seat.
  Saint Paul, accused of blasphemy by the Sanhedrin before a procurator, as a Roman citizen asks and gets to be judged by the emperor, and then is sent to Rome to be placed under house arrest in a home he has rented.
• In addition to faith, Jesus praises the military discipline of the centurion. And he never even speaks against the Romans, those whom many Jews - but not those who recommended him to Jesus - considered oppressors and exploiters.
• The Jews had already been in contact with Rome since a long time, they had their synagogue in the city as early as the 2nd century BC, because in Rome the freedom of trade, residence and religion was absolute, as long as the prerogatives of civil power were not harmed.
• Gnaeus Pompeius' Romans had been called by the Jews themselves before the time of Herod the Great to be freed from their kings who oppressed and massacred them.
  Moreover, Herod the Great himself had been raised and educated in Rome and prepared to reign in Palestine on behalf of Rome.
• In exchange for the help that an army of Jews who had set out specifically from Jerusalem had given to Julius Caesar, freeing him from the siege of the Egyptians in Alexandria, the Jews had obtained from him the privilege of not seeing the insignia of the Legions raised in Jerusalem, with images of their supreme commander, whom they regarded as idolaters.
• At the time of Jesus, however, intolerance against Romans was rising up. The Jews had forgotten their past troubles. But I believe that basically the feelings of hatred and ingratitude were due to the fact that the Romans demanded the taxes, which they collected through their revenue agencies, for example St. Matthew was a Jew who collected taxes on behalf of Rome.
  Obviously the fact was particularly hateful for a Jewish taxpayer of the time, even if the Romans defended Palestine against invaders, carried out public works, and guaranteed freedom of movement and trade throughout their world.

Holy Gospel of Jesus Christ according to Saint Matthew 5,38-42.