The phrase "nasty breakup" refers to a situation where a romantic relationship ends in a very unpleasant and hostile manner. It typically involves arguments, hurtful words, and negative emotions between the people involved. Full definition
She rose from immigrant roots up the industry ladder to become creative lead of her own multimillion - dollar women's wear fashion brand, and then endured a series of nasty breakups — first with her ex-husband and then with Jones Apparel Group, the fashion behemoth that licensed and marketed her creations. (inc.com)
Otherwise, you may be headed for disaster (and a nasty breakup). (entrepreneur.com)
Some men go back into the dating scene after a nasty breakup and it's too soon — they air their dirty laundry and share what they're not looking for. (hookupland.com)