I'm there with you. At the end of my first week I pretty much went into full panic mode about all the things that would lead to my failure. I think it's normal to see the mountain of work that you're responsible to master, feel like you won't meet the expectations, and totally freak out. You just have to take it one day at a time and just stay on top of your reading and studying.
If you haven't done it yet, then you need to organize your days. Make a schedule. You have 24 hours to work with. How many do you need to devote to sleep? Don't skim on it. It's important to keeping you healthy, focused, and feeling mentally good. So after sleeping hours, split up the hours left to organize your waking time. There are fixed hours like class time and traveling to class. Work with the rest of your hours to set up a routine for eating time, play time (you still need some fun!), other life responsibilities, exercise time (at least a walk for your overall well being), and then of course hours of study time. When you set up a routine where you know you will study between, say, 4pm and 6pm with 10 minute breaks within each hour, then you will make a point of studying every day. This is what's worked for me. Especially because I quit my job and it felt like I had both too much time and not enough time. A schedule was just muddy in my head but after I broke it down on paper it put more focus on my strategy. I think I felt overwhelmed at first because I had a vague idea of what I needed to do and not enough direction on how to do it.
I have several study chunks in my day with other activities in between. So I study for about 5-7 hours a day, on average. I felt so overwhelmed with the amount of reading but after I set up a schedule for myself, it felt like I was making progress. I'd check off the chapters in my syllabus and I felt like I was moving forward. So that would be my advice to you. Organize!
Ok, so I've rambled on a bit but bear with me a little longer. Because the second thing I felt was that even though I was doing all the reading, it didn't seem like I was retaining enough info or actually understanding it. So when I get to a point where I feel caught up with the reading, I devote some of my study time to review. I make flash cards to review on my own, ask someone to quiz me, and do all the critical thinking and multiple choice q's at the end of every chapter. Do I remember every single little thing and definition in the book? No. Did I think I had to? Yes. But those were my own expectations, not my instructor's. So I got over it and started to focus more on mastering the material in lecture and in the power points. Read the chapter for an overall idea, hone in your studying to the material your instructor focuses on.
Finally, I started a study group and that's been helpful to verbalize my understanding of the material and to get other perspectives. One of the girls in the group is so good with those NCLEX types of q's so it helped me start to understand that kind of style when she explained her thinking and rationale. Oh, and there are two book I found helpful in just understanding the structure of those types of q's. They're called Fundamentals Success and Test Success. They have previews of the book on Amazon and even the stuff you can see without buying is really eye opening. So that might also help with your anxiety.
And breathe! Good luck!