Why does Willy get upset when he sees Linda mending her stockings?

Willy becomes angry with Linda when she's mending stocking because, he's reminded of when he gave stockings to the "Other Woman" and Biff asked why he was giving away mom's stockings. Willy wants to start new and not have stuff mended. He wants to give Linda new stockings, so he's not reminded of the past. This is important because we get a glimpse into the Willy who wants to KEEP what he has; he doesn't want to lose his wife, but yet he doesn't want to fess up to his mistakes.