All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad, sallallaahu`alayhi wa sallam, is His slave and Messenger.
Masturbating through wife's hand or her body is permissible, since Allah allows a husband and wife to enjoy with each other as they wish provided one should avoid having sex in her anus or in vagina during her menses.
As for swallowing a husband's sperm, it is contradictory to sound nature and good manners.
Moreover, few scholars believe that sperm is impure; based on this opinion it is unlawful to swallow it. However, this opinion regarding the impurity of sperm is weak.
Allah knows best.