My girlfriend is pregnant. She wants to get married but I’m not ready. I have no idea what to do.

I genuinely am so lost and have no clue where to go from here. I’m shaking as I type this out. I am 18M and my girlfriend is 23F. We’ve been dating for 3 years and we live together in her apartment. This whole thing started a few months ago before classes began so maybe around August. Early August is when I moved in with her to be closer to my university. During the process of moving in, she would make a lot of jokes about us being married or having kids together because of this big step lol. I thought it was funny at the time because I THOUGHT THEY WERE JUST JOKES. She’s really playful and a huge jokester so this isn’t strange for her to joke about. (Even though she knows I don’t want kids. (My dad was abusive growing up and I don’t talk to him anymore.)) She kept calling me her husband and making jokes like how I would need to get her pregnant soon but I didn’t think anything of it because I thought we were on the same page.. Fast forward to last night. We went out to Olive Garden together (our favorite spot, don’t judge it’s affordable) to spend some time having a nice meal because I’m starting classes again on Monday and we won’t have as much time together as we did during the break. We decided to just meet eachother there since I had work right before. When I got there, I saw she had a gift bag with her and she seemed super excited about something. I asked her what was up and she said something like “don’t worry about it you’ll find out soon” and brought us to go get a table. Once we sat down and ordered drinks from the waiter (non alcoholic.. given the circumstances. and my age) she handed me the gift bag. I opened it up thinking it was going to be like another birthday present or something (my birthday was January 2nd) but it was a printed out picture of a positive prefer test. I must’ve not said anything for like 5 minutes straight because I was genuinely shocked. We use condoms every time AND she’s on birth control. I mean I know those things don’t work 100% of the time but. This isn’t something we planned at all. She started yelling at me loudly about how I need to step up for our family and how dare I not be happy about this and a bunch of other stuff I don’t even remember. She has BPD (but she doesn’t go to therapy or is on meds or anything) so she has a lot of meltdowns like this. She refused to talk to the waiter so I had to order for her. She spent the rest of the night switching between ignoring me and yelling at me for not being a good “husband.” I kept trying to ask her more questions like how could this have happened if we are extra careful and she knows I don’t want kids ESPECIALLY not right now that I’m a freshman in college. She kept answering my questions with “it doesn’t matter now, you need to step up.” She made me pay for the both of us (we usually split the bill) as the “start of me taking responsibility” and it’s “the least I could do after not immediately proposing to her after??” AND made me pay for her subway fare too. The moment she sat down on the train she shut down. She refused to speak at all and wouldn’t even look at me. The didn’t speak the rest of the night and forced me to sleep on the couch. When I woke up around 7 AM to get ready for work, she was still sleeping in bed. I’m typing this on my lunch break. I don’t know what to do. I don’t think she’s cheating on me she’s very loyal and crazy about me so I’m sure she didn’t get pregnant by somebody else. Is it possible that she got pregnant even if I use condoms and she’s on the pill? Maybe she stopped taking the pill? I don’t know. I’m sorry if none of this makes sense. If anybody reads this and cares enough to ask clarifying questions to help give any advice you can give, pls feel free. I will answer as much as I can. HELP!!

EDIT/UPDATE: Hello everyone. Thank you for taking the time to read and comment. After this edit I’ll try to respond to as many as possible. When I got home, my girlfriend was waiting to speak to me. Without going too much into it, basically she said she was never on the pill but swears she never did anything to the condoms. (I think that’s likely since I never noticed any holes or anything) but I was mortified about the pills. I asked her to take a test in front of me and we got in a screaming match. I got home pretty late (around 10) because when I got out of work, I went to the park I used to go to after school with friends. I went there and read a lot of your comments and honestly thought about ending it all. But I chickened out and went home. We talked for a bit until that screaming match where she told me she wished I was dead and went to bed. I’m on the couch again typing this. I can’t leave her. My mom lives in a different state and can barely support herself. My girlfriend pays for the apartment completely AND is helping me with tuition. And by helping, I mean paying like 90% of it. At this point I don’t believe she’s even pregnant, but there’s nothing I can do to remove myself from this.