Every person has their flaws, but I've always admired and felt sorry for Catherine, too.  Even though I love Anne so much and Catherine stood for almost everything that Anne didn't, it always eats at me a littlle when I read that Anne was unkind to Catherine.  Yes, Catherine went a little overboard at times, and yes, Anne was in a very stressful situation trying to keep Henry at bay until marriage, but I've never quite figured out why she began to be so against Catherine.  Perhaps because Anne was so against the corruptions of the Catholic Church and thought that Catherine lied about her virginity and therefore the papal dispensation was invalid??

I always felt sorry for Katherine.  She loved Henry and kept her marriage vows sacred to the end.  She loved Henry even while he traipsed his mistresses in front of her.  Her religious beliefs guided her throughout her life.  She never wavered.  I agree that she would have been treated fairly in a divorce, but she stubbornly stood her ground.  In the end she died hidden away in a cold, damp castle, never to see Henry or her daughter Mary again.  She paid a very steep price for her faith. 

Anne was in a very tough situation.  Henry was trying to get her to become his mistress, then his wife.  The Catholic faction, Katherine's friends wanted her gone. (and they weren't nice about it) The reformists wanted her on their side. The stress would get to any one after a while.  I don't think she thought Katherine was being honest about her first marriage.  She may have thought Katherine was lying in order to keep the divorce from going forward.  She saw how upset Henry was about the delay in the matter and followed his lead.  I think she was very frustrated with the whole thing and in her mind Katherine was to blame for most all of her troubles.  Therefore, she took her frustrtion out on Katherine.

As much as I admire Anne, she had her faults just like the rest of them.