I think Amber has evolved for a new cycle, albeit miniature; Inbetween #3 (indignation) and #4 (manipulation).
3.5 Cunt.
Amber throws all of her exgirlfriends under the bus. She neglects her audience and speaks back with aggression. Showing off. Lies or revealing partial truths (ex. Walmart Scooter stuck incident, Destiny's cheating allegations, Becky refusing to travel, Becky never doing anything to help Amber, sex life, asswipegate). There's also a ton of jealousy, more than normal. Amber has never been so "full throttle", brazenly cunt-like, until lately.
Amber is an emotional vampire, after all, so maybe she's just absorbed wipey's hot-headedness to fuel the fire, too.