NBA star Jason Collins' ex-fiancee called in to "TMZ Live" today, telling us he threw a wrench into her life plans when he pulled the plug on their wedding back in 2009 ... but it's not all negative ... in fact, she's grateful for how things turned out. And get out your notebooks ... "Shark Tank" real estate guru Barbara Corcoran explains why Taylor Swift got ripped off when she bought a $17 million Rhode Island mansion.