Rihanna hit the bottle on Tuesday (10Jul12) as she prepared for her grandmother's funeral in Barbados.
The singer posted a photo on Twitter.com and apologised to her late 'Grangran Dolly' for using alcohol to ease her heartbreak.
She wrote, "I had to!!! Sorry granny."
In the snapshot, Rihanna posed without make-up and looked exhausted.
She has been dogged by health issues linked to extreme tiredness, dehydration and reports she has been overdoing her partying in recent months.
Clara 'Dolly' Braithwaite lost her cancer battle in New York last month (Jun12) while her granddaughter was on tour in Europe.
Rihanna cancelled a concert in Spain last week (ends06Jul12) and flew home to Barbados be with her grieving family members. She also attended a memorial in New York before flying to London for a performance at the Wireless Festival on Sunday night (08Jul12).
She has since returned to the Caribbean for the funeral service.
She arrived at the sombre event dressed in a modest black dress, wearing her hair high and clutching a purple notebook, presumably filled with remarks and recollections she would share with fellow mourners at the ceremony.