Hello everyone!

My brother is 25 has two kids with his ex fiance. He had a vasectomy on August 9th. They recently broke up at the beginning of September. On my brother's 25th bday October 6th, he was drinking and had sex with some girl twice. 1st time with a condom, 2nd she was on top but he pushed her off/pulled out.

Welllll.... she texted him October 28th saying shes pregnant and its his, and that she hasn't slept with anyone since January....

Also a week prior to that text my brother and his fiance got back together to work things out. Now she left again bc she doesn't know what to do/think about the situation.

Could she be pregnant by my brother or do you think she was pregnant before him ?