Roxy - good or bad?

In class, we brought up questions about Roxy and where she stands exactly.  Throughout the book, we see Roxy’s morals/personality flip-flop.  As a general idea about Roxy, we see a dichotomy between a loving mother and a greedy individual.  Initially, the persona of a loving mother comes out for she switched “Tom” and “Chambers” in order to save her son from being sold down the river.  She wanted to see her son have an enjoyable and successful life.  However, her son “Tom” becomes spoiled and cruel.  Once Roxy became a free slave, she saved up money but her bank lost all her money, so she goes to “Tom” and begs him for money but he couldn’t due to his gambling debt.  Roxy told Tom to sacrifice her (sell her as a slave in a local area) in order to create a better life for Tom.  However, Tom betrays Roxy and sold her down the river.  Luckily Roxy escapes and makes her way back and as a result, Roxy began to blackmail “Tom” in threatening him to reveal his true identity, a nigger, to the rest of the town.  So Tom pays Roxy a sum amount every so often.  He gets the money from his thieving escapades that Roxy plans out.  This is when I began to view Roxy as a “bad person.”

In one of the earlier chapters when Percy Driscoll discovers that things are stolen from the house and blames it on his slaves.  All of the slaves confessed they stole something.  Here we see that Roxy is a “good person” by not stealing and has recently become religious.  But at the end of the book, we see that Roxy is part of these thieving plans and that she becomes less of a loving mother and more of a greedy individual, basically more self-interested and less about her son. I think this may be due to the fact that once she has seen her son has become this cruel individual that she gave up hope.  What do you guys thinks?