Just a thought but had this man followed her up with a meeting anytime in the weeks and months after the sex he would have found out the OP was carrying a baby. Why is she responsible for telling him. I mean it is great if she had chosen to do so, and many, many women will choose to tell the man. But not all will.
TinselTwins Re "Italiangreyhound, it's no logical, that's how I know it is her rationalising it."
What is not logical? Do you honestly think most men would be delighted at the idea they were to be a dad during a heavy university course by a one night stand? Would many, many men prefer not to know? I think it is easy to see that many would prefer not to know.
Also "... she's also said that she was afraid of being percieved as a liar and a gold digger"
It is very, very clear to me that the OP is still fearful of this and that is one thing holding her back.
I have no idea if they would have persevered her as such; personally I would not give a fuck what they thought but the OP sounds a lot nicer than me! She seems to be genuinely worried what these relative strangers would think of her. After what she has lost I would not be at all worried about their views of me.
TinselTwins Re ".. but maybe it's easier for her to believe that she did him a favour even though she didn't."
According to you, this is your view, as mine is mine, and the OP's view is she did what she thought was best for him.Whether what she did was for his best, truly - I don't know. But whether what she did was in her mind for his own good, I don't know but I choose to believe her.
OP you need some counselling and potentially some assertiveness training too so that you can start to feel better about how you handled things. You are so young, you did what you felt was right and you need to stop feeling bad about the way you handled your part of this, who knows how any of us would have acted.