Shadowboxer
(2005)

Mikey (Cuba Gooding, Jr.) and his stepmother Rose (Helen Mirren) are lovers and contract killers.

Mafia boss Clayton (Stephen Dorff) hires the pair to kill his pregnant wife Vickie (Vanessa Ferlito). Rose and Mikey are about to kill Vickie when she goes into labour. Rose helps birth the baby and tells Mikey they have to protect Vickie and her newborn son.

The four end up living together in Philadelphia. Rose is diagnosed with cancer. At baby Anthony’s first birthday party, Rose decides she wants to die during her happiest time rather than continue suffering. Rose makes Mikey promise to take care of Vickie and the baby.

In the nearby woods, they have sex and Rose convinces Mikey to shoot her as she reaches orgasm.

Mikey, Vickie, and Anthony live in safety until the boy is around 10 years old. Clayton learns that his wife and child are still alive, and captures and tortures Mikey.  Clayton is about to kill him when he is shot by Anthony.

Mikey, Vickie, and Anthony are seen driving away; when Mikey warns Anthony to watch out for people like him, the boy responds that “we’ll kill them.”

Thanks Emily B!