>OP You wanted impartial advice so here is mine.
First, since we don't know this girl there is no way for us to judge whether she is a truthful, trustworthy person or not. So, the first thing I would recommend is to verify that she is in fact pregnant. Stranger things have happened. If she is pregnant and determined to keep the baby you really need to go to your parents and ask their advice on how to approach this. I hope they can be there for you. You are heading into your third year at uni but so is the girl (not sure what year) does she want to give up her education for a baby? You've made it clear you don't. Abortion is an option but help this girl to see that adoption is a really good viable option as well! Maybe for personal reasons abortion isn't something she can do (does that weigh into her decision to keep it) but with adoption she (and you) can select the type of adoption. So many great couples, who are ready to be parents, would be thrilled to raise the baby. Open adoption is great in that the birth mom (and I'm sure dad if he wants) can know how the child is doing, receive updates and in some cases be an active part of the child's life. In that situation you both can finish uni, get established, and be prepared for when you are ready to have children.
Who knows if this girl got pregnant while on the pill, it does happen!! You don't KNOW that she lied. Take it from me I was a surprise! I was the unplanned for fourth child...... my parents were done having kids (or so they thought) after three. They were using birth control.
You know this girl, you know her character, you probably have a good sense of if she is someone who is truthful or someone you can see being deceitful. But, if you think she's the truthful girl then be there for her.... she's scared out of her mind! Definitely work through this with her, in these early days at least, even if it means you ultimately don't want to be part of the baby's life.
In theory you did nothing wrong.... you thought she was on the pill. Now you, and every guy reading this thread, knows that ultimately it is up to you to protect yourself. Pregnancy and certainly STI are possible on the pill.
I don't know legally/financially what responsibility you have if you claim you want no part of the baby and walk away. It may be that easy..... I just don't know. Lastly, if she does decide to keep the baby and is demanding support from you then I'd encourage you to have paternity test done upon the baby's birth, again to verify.
**My advice: verify pregnancy, strongly consider and encourage adoption over her keeping the baby or abortion (just my opinion), be open with your family and let them help you through this, be there for her during these early days while you both figure out what to do, never engage in sex (until you're ready for potential fatherhood) w/ out protecting yourself. Sex with a condom may not be ideal but it is a whole lot better than receiving the "I'm pregnant" call., verify paternity.
Sorry this is so long..... I know you feel terrible, trapped and angry. Sorry you're having to deal with this. Good Luck.
P.S. I know this because my brother went through this a few years ago.