How did Dr. Flint’s wife influence Harriet’s life in Incidents in the Life of a Slave Girl?

Mrs. Flint shows Harriet just how morally corrupting the system of slavery really is. Instead of holding her husband accountable for his serial philandering, she puts all the blame onto Harriet, seeing her as a craven temptress rather than a cruelly exploited slave.
To some extent, Mrs. Flint is also a victim of the peculiar institution in that it encourages white men to force themselves upon their female slaves, thus breaking their marriage vows. But instead of developing a sense of solidarity with Harriet, Mrs. Flint hates her guts, seeing her as responsible for her husband's infidelity. Not only that, but she actually joins with her husband, the man responsible for all her feelings of jealousy and rage, in trying to track down Harriet after she escapes.
What all this demonstrates is the corrosive effect of slavery on the human soul, how it turns traditional notions of right and wrong completely upside-down.