Sad because best friend is pregnant

Jess
I was born in the US yet I grew up in Mexico; one of my parents' neighbors had a baby about 4 months after I was born. She became my best friend since we lived closed, went to school together until 10th grade (then I moved to the US), we grew up as ladies together, I spend the day at her house most of the time and vice versa. You know, like a true old, good best friend. I'm only 17 but been working and studying since last year so we don't talk much. I've been really busy but a little after we finished 10th grade she got a boyfriend. I felt jaleous because he was older and a total jerk. We didn't text much but every summer that I went to visit she would always be mad, sad, and tired over him but they always went back. She's the youngest of 6 children but she had much more freedom than your typical 15 year old, plus, her body was gorgeous. Also, in her family they all dropped college and got married because unplanned pregnancy except for 2 siblings. Anyways... about two weeks ago I saw her social media and she apparently (again) broke up with her boyfriend. Wasn't a surprise. Then like a week after she puts a picture with him. Not a surprise again. Well yesterday she puts a picture of him kissing her whats seems to be her stomach. I was shocked. You also saw a ring on her hand. I felt shocked since she's only 16, he's a jerk, and she was doing great in school. I called but she didn't answer. Then I called another of our friends (another neighbor). She confirmed to me that she was pregnant and about to get married. I started crying and I felt so bad. She's only 16 and like a sister to me. I just can't believe that my worst nightmare is happening to her. I'm paranoid about pregnancy at this age and before marriage so I take a lot of care but still get really scared. I've been thinking about what happened, why she didn't told me, what's she's going to do... maybe more than her. Is this normal? I keep overthinking maybe because I had sex but it was protected and he even pulled out with the condom but some cum dropped in my pubic hair but I was also on my period... I'm so sad and overthinking.