The girl (23F) I've (24M) talking to, pulled a pregnancy prank on me. What does this even mean?

I (24M) have been friends with a girl (23F) whom I met online about 8 months ago. We chat regularly and have a lot in common. We're both in the tech field, both single, and often talk about our day-to-day lives, work, and personal issues. She trusts me enough to ask for advice on life-related matters, and a few months ago she even told me about her promotion before she told her own family. Overall, we've built a close friendship and I consider her a very honest and trustworthy person.

A few days ago, after about three days of silence due to work (which is normal for both of us), she suddenly texted me saying she was pregnant. I was completely shocked because she had always told me she was a virgin. She then told me that she had taken both a pregnancy test and a blood test and that both were positive. When I asked who the father was, she said it was a colleague of hers and that they had slept together three times. She went on to explain that she had trusted birth control pills too much, that she hadn't spoken to the colleague in about a month, and that he had previously wanted her to marry him and move into his house. The whole story sounded completely out of character based on everything I knew about her, and I was honestly stunned that something this major could have happened without her ever mentioning it before. About five minutes later, she revealed that she was joking and had made the whole thing up. I was furious. She then laughed and said that if she were ever actually pregnant, I would be the first person to know. I clearly told her that I was angry about the prank. After realizing how upset I was, she said she would give me some time to process it.

My question is: what do you make of this situation? Was this simply a badly judged prank, or could she have been trying to gauge my reaction for some reason? I don't know if I was extra emotional because I was already stressed from work that day, but I genuinely felt shocked, betrayed, and angry because I trusted her and immediately took what she said seriously. Am I being too sensitive here, or would most people react similarly to a close friend making up something this significant?

TL;DR: My friend faked a detailed pregnancy story as a prank, I believed it and got upset—now I’m questioning whether I overreacted or what it says about her.