Had I known the author, I would have known the event. This poem is a beautiful dirge to your sister.
My original comment:
Rhyme scheme: a-b-a-b-c-d-c-a-a Meter: 9-10-9-9-9-9-9-10-9
The message here is again one of loss, but in this case the speaker focuses on the needs of others ("Someone had to pretend to be strong"). On the other hand, the message is simple and direct yet without anything new to place on the groaning board. It would help to set out the relationship (mother, daughter, grandmom, Mother Superior). The poem begs particulars to bring the reader into the veil of mourning.
EDIT: Graphic tribute. The poem & the explanation become a chalice on an altar.

"This poem makes me think of a family member or a friend sick in the hospital, and that those closest have nothing to do but wait until they pass away, and the closing line makes me want to cry. It's so beautiful yet filled with such sadness simultaneously. I"Someone had to pretend to be strong" Hands down my favourite line. This really stood out to me because it is so relate-able. Too often we try to be strong when in reality we're coming apart underneath the act. I wasn't so keen on the constant use of filler words, such as "I, she" etc along with the sudden change in rhyme scheme as it altered the flow slightly. I felt it took some of the emotion away from what could have otherwise been an extremely moving poem. "

:)