What do you say of a man who is highly strict with his sisters to the extent that he ignores his sister for 5 months for speaking to other men who are just her colleagues? When he married he married a woman of disgusting morals who commits what is almost Haram, insane relationships with men and so on and he is aware of all that.

Praise be to Allah, the Lord of the World; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

It is a brother's duty to be jealous for his sister, since she is part and parcel of his honor and reputation that he has to protect and defend.
The Prophet (Sallallahu Alaihi wa Sallam) has clearly stated that sense of honor/devotion is among signs of belief.
Abu Hurairah (Radiya Allahu Anhu) reported that the Prophet (Sallallahu Alaihi wa Sallam) said: "Allah is jealous (for His prohibitions), a believer is jealous (for his honor) and Allah becomes jealous if the believer violates His prohibitions" . [Reported Imam Muslim ].
So, if a brother/father accepts that his sister commits Haram, this means that he has lost his sense of honor. In such a case, he will be prevented from entering Paradise. In this vein, Ibn 'Umar (Radiya Allahu Anhu) reported that the Prophet (Sallallahu Alaihi wa Sallam) said: "Allah has forbidden three classes of people to enter Paradise: (1) a habitual drinker, (2) an ungrateful one, and (3) one who keeps silent concerning his wife's dissoluteness and lewdness" . [ Ahmad and others].
Such a jealousy/sense of honor must be in the heart of every responsible person towards his mother, wife, daughter, aunt and so on.
Therefore, we state that conduct of the person mentioned in the question with his sister is legal, sound and even a duty.
In addition, keeping silent concerning his wife's Haram behaviour is not only wrong but also Haram, and person who does such an action will be afflicted with the Prophetic threat mentioned in the above Hadith.
Know that, according to Islam, there is no friendship between the two different sexes. As a rule, there must be segregation between men and women, since mixing causes bad consequences. So, our brother, you have to advise your wife to avoid what is Haram and to hold her back such Haram deeds by all possible means even if it becomes necessary to beat her.
Otherwise, no good Muslim accepts being the husband of a wife whose behavior is bad.
Allah knows best.