I agree with you narangi_ and share a very similar view point of each of the characters you mentioned.
For those who are calling Ragini evil, this is a bit drastic!, please take the situation within it's context. I know some people cannot bear sadhna in hardship, thus anyone who contributes to that is classed as evil- this is a bit harsh.
If ragini was so evil, she could easily just ignore the fact that she knows the truth now, she could continue to reject sadhna as she (ragini) is now the favorite bahu of the rajvansh. However she will never do this, when reality as become apparent to her, she will stick up for what's right- because she now knows it! she will defend sadhna against all odds, because sadhna's inentions are clear to her now.
Her biggest mistake was misunderstanding sadhna, and not realising her intentions. But does that make a person evil?! had she pusposely accused sadhna, while believing that sadhna was right, then ok perhaps you could label her this way.
Poeple are using the word 'evil' too lightly. Evil is when a person has cruel intentions, and therefore performs bad action to cause harm and destruction wihout any just reason. This is then followed by good no longer posessing then, but evil consuming them as they use any means to achieve their aim. Is this really ragini?