Can't file 2019 taxes because I don't have the AGI from 2018 - exhusband not responding to requests for it

Hello!

 

My niece went though a contentious divorce in 2019, but her husband filed the 2018 taxes and just sent her what he said was her half of it.  She never saw her 2018 return.  Now, she can't efile to get the stimulus check because all sites require her to know her AGI from 2018 and he won't respond to her at all when she's asking him for it.  She requested a transcript from the IRS weeks ago, but it still isn't here.  What are the best options to get her taxes filed ASAP so her stimulus check doesn't get deposited into his account?