I think my babymomma slept with someone while she was pregnant

First, to clarify, we weren’t together from the time she was 5 months to 8 months pregnant. We seemed to always bump heads and she treated me kind of shitty so I left and told her I’ll still take care of my baby. I ended up going back when she was 8 months pregnant (march 2024) and stayed with her until August of 2025 then we split again because it was toxic. During our time apart (8 months) I was informed that she slept with someone while we were apart and she was pregnant, supposedly around 8 months pregnant. When I confronted her about it, she admitted that she let the guy give her head but they didn’t do anything else. So I confronted the guy about it and he said they had sex and it was just a one time thing. But she swears up and down they didn’t have sex, he just gave her oral because she couldn’t have sex at the time without it hurting which I believe because we couldn’t when I came back around without it hurting her. And supposedly that was close to the same time. But he swore she was lying and even said she gave him head too, but she doesn’t like giving head and really isn’t that great at it. Then she keeps saying “I wouldn’t tell nobody I gave a pregnant girl head and got blocked either that’s embarrassing”. Then when I told her what he was saying she texted him going off on him for “lying” on her. He sent me what she said and said this is the craziest shit he’s ever been a part of she’s believing her own lies. She still swears up and down all that happened was him giving her head, but I really don’t know what to believe. Could yall help me out?