Who is Anne of Cleves from The Six Wives of Henry VIII and what is their importance?

Anne of Cleves was Henry fourth wife.... and lifelong friend. Henry found Anne ugly and wanted out of the marriage at all costs..... Anne was unafazed, as long as she didn't have to go home. Henry set her up in a nice house, and she willingly gave him his divorce. Anne spent a lot of time with Henry's children, and Henry considered her a sister.