What does Candide think the old woman’s history means for the theories of Pangloss?

All the characters in Voltaire's Candide encounter suffering. However, the old woman is the character that suffers the most.
She is introduced as a means to contradict the optimistic but unjustified view of the world that Pangloss has. This view has been passed on to Candide through the teachings of Pangloss.
Pangloss has a naive, unrealistic, and foolish vision of the world. Candide initially shares this vision, but the old woman's story forces him to question these theories.
The old woman has been raped, beaten, sold, and mistreated in every possible way. For this reason, she believes that life is not often ideal. Despite her misfortunes though, she loves life and remains quite optimistic. She states:

A hundred times I wanted to kill myself, but always I loved life more. This ridiculous weakness is perhaps one of our worst instincts; is anything more stupid than choosing to carry a burden that really one wants to cast on the ground? To hold existence in horror, and yet to cling to it.

Her optimism is rooted in hope for a better future mixed with love for life, but she is also very aware of how hard life can be. Candide realizes that it is possible to be an optimist even after experiencing suffering, but this involves a different attitude towards life. It is important to be aware and to recognize that the world is not as perfect and wonderful as Pangloss makes it out to be.