Divorce was difficult to obtain in nineteenth-century England, although it gradually became easier as the century went on. At the time Dickens wrote
David Copperfield, however, a woman couldn't actually separate from her husband on grounds of abuse alone, so it's likely that Miss Betsey’s husband also had an affair. Regardless, his treatment of Miss Betsey reveals the vulnerable position of married women in the nineteenth century; he was able to squander her money, for instance, because a husband gained possession of all his wife's property on marrying her.