How did Cleopatra sacrifice herself?

Cleopatra put a cobra on herself because she couldn not bear to live without Mark Antony . What happened was she ran away and locked herself in a tower so she wouldn't see the battle go on. She told her servant to tell Antony that she was dead. Antony believed it so he stabbed himself because he wasso upset that she was dead. When Cleopatra heard this she put a cobra on herself, the cobra bit her. Both ended up dead.