you file form 8857 which is separate and apart from your 2025 return - innocent spouse
https://www.irs.gov/pub/irs-pdf/f8857.pdf
i have provided a link to a webpage that has more info
https://www.insightlawfirm.com/blog/2025/01/do-i-qualify-for-innocent-spouse-relief/
see this IRS webpage for clarification of injured vs innocent spouse.
note that if this is a case of the balance of taxes due not being paid(rather than errors in the joint return), the IRS can pursue both parties. In this case it is not a DIY project. seek professional help.