Those who break relationships with relatives and adulterous women will not be forgiven
Hadhrat Ghouse A'adham (May Allah SWT be well pleased with him) narrates from his Shaykh with a continuous chain of narration:
Translation: The Holy Prophet (Sallallahu alaihi wa sallam) said: Allah (Subhanahu Wa Ta'ala) graces the skies of this world with His presence on the 15th night of Sha'aban and except Mushrik, hateful, those who hold the wrong 'Aqida, those who break relationships with relatives and the lady who does not guard their private parts forgives everybody.
(Al Ghunya Li Talibi tariqil haqqi, Vol. 1, Pg. No. 190)
This Hadith shows the importance of maintaining good relations with one's relatives. Breaking relations with them, refusing to talk with them, not helping them in their difficulties or not consoling them in distress, all these practices take one away from the Mercy of Allah (Subhanahu Wa Ta'ala).
If any relative breaks relations or does not treat one nicely, even then the ruling for that Muslim is that he/she should remain in contact with them even though those may not even talk properly. They should meet them cheerfully, should give them gifts etc. Gradually their misunderstanding will clear. The Holy Prophet (Sallallahu alaihi wa sallam) has specially urged us to meet and treat those relatives nicely who want to break away.
Translation of Hadith: Attach yourself to those who break relations with you and forgive those who oppress you.
(Mustadrak 'Alas Sahihain, Hadith No: 3873; Musnad Ahmed, Hadith No: 15065)
As far as the criminals are concerned, it has been clarified that if they repent before Shab Bara'at or even in Shab Bara'at, they will be forgiven.