I think my best friend lied to me about being raped?

[Natasha]

Over the summer my best friend told me about how in her first year at university she slipped up generally with her morals and hooked up with guys, and had sex with one, losing her virginity. The way she told me this initially was in a pretty light manner, and we were joking around and stuff.

She's always been devout to her religion, and believes in no sex before marriage, abstains from alcohol, dresses modestly, etc.

Please bear with me, i'm almost getting to the point - she is also very outspoken. I won't say of what religion or country, but they experience much corruption/discrimination. In school she was never afraid of speaking out, or making Facebook statuses about the wrongness of what her people experience, and openly discusses and defends them.

So she met this guy now in second year, and considers it a serious relationship. One, where she could "potentially see herself marrying him". One day she calls me during this second year, and tells me that the guy she lost her virginity to actually raped her. Immediately I couldn't believe it... why is this coming out now? Is it because she's trying to give her slip-up an excuse, to still be a virgin before marriage with the claim that it was stolen from her? she's such a spoken out girl, and would not let someone get away with doing something like that to her and keep quiet about it.. (these are all my speculations)

What are some thoughts about this? Is it right for me to doubt her? How do I go about approaching her possibly lying to me.. or if i even should?