Am I fucking tripping?

So my best friend who hooked up with my brother (TO BE EXACT) the 16th of this month, this was the only time bc she didn’t know him before that and we were all drunk and they did the do. So anyways she called me to tell me she’s pregnant, me thinking she’s joking or something I told her send me the pregnancy test, she sends it to me, one with her face in it so now I know it’s real but I’m like how is that my brothers baby?

It takes 2 full weeks to show a viable baby after sex and to even become pregnant and that was 12 days ago so it’s just really weird to me how her pregnancy test would even show up that early or at all? Like is that even possible unless she was already pregnant before him?

Her response to this was that she did one of those “early result pregnancy tests” from 6 days before her missed period and about how her period is supposed to come in 2 days and she usually spots days beforehand but didn’t and wanted to be sure and then boom.

I don’t fucking believe her. Am I gonna be an aunt or does it sound like she was already pregnant? She also says she hasn’t been with anyone else.

I’ll attach the exact photo she sent to me as well.

I don’t know why but I am really pissed right now.