How did Anne Boleyn treat Jane Seymour? I’ve read that she wanted Jane out of court but are there any known accounts of her being cruel to and/or confronting Jane?
There is the account of Anne Boleyn tearing a necklace from around Jane Seymour's neck:-
"It is currently traditional that at her first coming to court, Queen Anne Boleyn, espying a jewel pendant about her neck, snatched thereat (desirous to see, the other unwilling to show it) and casually hurt her hand with her own violence; but it grieved her heart more, when she perceived it the king's picture by himself bestowed upon her, who from this day forward dated her own declining and the other's ascending, in her husband's affection." Thomas Fuller (1608-1661) in "History of the Worthies of England".
Anne's horror and anger at seeing this locket is understandable when we realise that Henry gave Anne a similar gift when they were courting.
There is also an account of Anne finding Jane Seymour on Henry VIII's lap and Anne even blamed her miscarriage on the incident.
Jane Dormer, Duchess of Feria, and lady to Mary I, also reported "scratching and bye blows between the queen and her maid." Anne certainly saw Jane as a threat to her position, after all, Anne had been a lady to Catherine of Aragon and risen to be queen!