You can be a bitch without being "evil." In this case that would be her favoring her own children (probably not uncommon for step parents in the nobility, folks are obsessed with blood ties) but not actually being a murderer or co-conspirator. This far in I'd say the jury is still out on the whole thing though. I don't agree with the thought that it's too obvious to be true, for instance. Some people just get away with crimes despite them seeming so obvious.
Isn't most of the U.S. about 90% sure O.J. did in fact do it? Lack of proper evidence, tampering done by people investigating, that whole thing was a shit show from start to finish and if he did do it, he got away with it and went on to basically taunt people with that stupidly titled book he released and what have you.