How to prevent my soon to be ex husband from filing a joint return on my behalf

My soon-to-be ex-husband has the login information from our previous tax returns stored on TaxTurbo.  He informed me that he opened my 2023 W-2 and is going to file a joint return. I made it clear to him that  I am filing separately.  How can I ensure that he is not permitted to file a joint return with me?