Ok this is kinda embarrassing but I hope noone judges.

A little backstory: my husband and I broke up for 3 months last year and during that time he slept with someone else. They both confirmed that it was just one time and that he did wear a condom but it broke. That was 11/25/21. We got back together and finally posted it on social media a few days ago(3/17/22). The VERY next day the girl says she is now pregnant. She says she's 18 weeks which would definitely make him a possibility. The thing is, she sent me an ultrasound that says 22 weeks dated 3/16/22. She says it's a mistake?.... However I did a little stalking and went on her Facebook and she had another ultrasound that says 12 weeks 6 days dated 1/11/22... so the tests seem to be consistent.... could they both possibly be wrong?.. Or is there any way that he could be the father of that baby if they only slept together on 11/25/21? I don't want to believe that this girl would really lie about something like this but I just don't see how she's not. Please let me know what you think