Spiritual endangerment = staying with the bad scary apostate. Therefore, apostasy would be grounds for separation - I don't know about divorce.
*** w88 11/1 p. 22 pars. 10-12 When Marital Peace Is Threatened ***
Willful nonsupport is one basis for separation. When entering wedlock, a husband assumes the responsibility of providing for his wife and any children they may have. The man who does not provide for members of his household “has disowned the faith and is worse than a person without faith.” (1 Timothy 5:8) So separation is possible if there is willful nonsupport. Of course, appointed elders should give careful consideration to an accusation that a Christian is refusing to support his wife and family. Stubborn refusal to support one’s family may result in disfellowshipping.
Extreme physical abuse is another basis for separation. Suppose an unbelieving mate often gets drunk, becomes enraged, and causes the believer physical harm. (Proverbs 23:29-35) Through prayer and by displaying the fruitage of Jehovah’s spirit, the believer may be able to prevent such outbursts and make the situation endurable. But if the point is reached where the health and life of the abused mate actually are in jeopardy, separation would be allowable Scripturally. Again, congregation elders should look into charges of physical abuse when two Christians are involved in the troubled marriage, and disfellowshipping action may have to be taken.—Compare Galatians 5:19-21; Titus 1:7.
Absolute endangerment of spirituality also provides a basis for separation. The believer in a religiously divided home should do everything possible to take advantage of God’s spiritual provisions. But separation is allowable if an unbelieving mate’s opposition (perhaps including physical restraint) makes it genuinely impossible to pursue true worship and actually imperils the believer’s spirituality. Yet, what if a very unhealthy spiritual state exists where both mates are believers? The elders should render assistance, but especially should the baptized husband work diligently to remedy the situation. Of course, if a baptized marriage partner acts like an apostate and tries to prevent his mate from serving Jehovah, the elders should handle matters according to the Scriptures. If disfellowshipping takes place in a case involving absolute endangerment of spirituality, willful nonsupport, or extreme physical abuse, the faithful Christian who seeks a legal separation would not be going against Paul’s counsel about taking a believer to court.—1 Corinthians 6:1-8.