Am I sinful for not visiting my family and severing ties with them, in avoidance of hearing what displeases Allah, and in preservation of my religion and marriage, after failed attempts at reconciliation?

If the situation is as described, then refraining from associating with them is not a severing of kinship ties; rather, it is an abandonment of gatherings of evil and a preservation of one's religion. It is advised to offer them counsel and remind them of Allah the Almighty, even if through sending beneficial books and tapes.