Think of it like this - you have power over reducing her pain .. but you must exercise diligently !
Btw - faith (scriptures) comes in handy in such dilemmas . If you have heard of 'Bhagvad Gita ' - it says - Body is like clothes - it must perish - the soul however , never dies ..
Quote > As a person sheds worn-out garments and wears new ones, likewise, at the time of death, the soul casts off its worn-out body and enters a new one.
Link to original verse with translation..