After you file

I just found out my ex boyfriend claimed me as a dependent on his tax return 2019. 

on 2018 He put me also as his dependent but that was when we were together ..... but we broke up later on at the end of that year so he doesn’t have the right to keep claiming me as his dependent. He told me he “didn’t realize the system of his tax accountant kept my information” so he filed his taxes and he didn’t know that I was still there as his dependent, so I called the Tax corporation who did his taxes and they told me he is lying because they always ask for updated information.... I’m an american citizen and now I don’t know what to do because since he claimed me as his dependent I can’t request my stimulus check, I’m very worried because I lost my job, my ex basically stole my money and I don’t have money at all. What Can I do?