Shivon Zilis tells jury that Elon Musk was her twins' secret IVF donor — until Business Insider found out Shivon Zilis at court Bloomberg/Bloomberg via Getty Images It's week two of Musk v Altman, in which the Tesla CEO seeks $134B from OpenAI and Microsoft. Former OpenAI board member Shivon Zilis took the stand as a key witness for Musk. First order of business: clearing the air on their complicated and once-secret relationship. Former OpenAI board member Shivon Zilis was asked under oath on Wednesday to clear the air about her complex, once-secret relationship with Elon Musk. Zillis, a decadelong executive at Musk's companies and the mother of four of his children, testified as a witness in the ongoing Musk v Altman trial in federal court in Oakland. She said sometime after she joined OpenAI in 2016, she had a romantic "one-off" with Musk, a cofounder and major investor in the company. They then became friends, she said — and co-parents.…