SAN FRANCISCO, Ca (AP) – Elon Musk’s tumultuous $44 billion bid to buy Twitter is on the verge of collapse – after the Tesla CEO sent a letter to Twitter’s board saying he is terminating the acquisition.

Twitter says it will sue Musk to complete the merger he just rejected and is “confident” it will prevail.

It is not entirely clear whether Twitter’s board will accept the $1 billion breakup fee or if there will be a court battle over the deal.

The possible unraveling of the deal is just the latest twist in a saga between the world’s richest man and one of the most influential social media platforms.