I'm going to be separated from my girlfriend temporarily and it's making me so dreadful

I don't know where to begin but, we've been together for over two years now. I've been living with her ever since we pretty much met (I was 21 when we met, I'm 23 now), I was in such a toxic place before I moved out with her (which is in another country, but very close to mine; about 4-5 hours by car).

Since I have had a horrible experience with school; bullying, dropping out due to depression and the such, not having a degree in literally anything cause my school never gave me one, not even a simple highschool degree, I've decided to do online school with the help of my girlfriend. I've done that for nearly the two years I've been with her, then that dreaded day came where I had to do my exams. 

Turns out my school had misinformed me about the necessities for my exams. They've never provided me information or resources to do my exams. In the end I would have to read 36 books (in around 3-4 months) in different languages and the such, all that for my exams. I couldn't do it, so I stopped that school a couple months back. 

Right now I have no other choice but to be away from my girlfriend. I'm now stuck in a toxic environment where my mother always gets angry at everything, loud pets and a brother that only gets drunk. All of this is so that I can try and get some job experience which I don't have (I've never worked). Sure it's temporary, maybe it takes 3 to 5 months, and I can visit my girlfriend everyday I might not work or have any appointments here. This is all so that I may or may not have a chance at living with my girlfriend and work there. 

But it's just so hard. The day I had to go back to my country was the most dreadful day of my life. But the weirdest part was that I was fine for a while after coming back. Not until my girlfriend came back to visit me for three weeks, I started feeling too attached again, I got so worried and so panicked of us separating that I stopped watching a show I liked, my appetite is gone 95% of the day and I ball my eyes out in front of her and have these full blown panic attacks. This started happening around a week ago until my mind started realising she was going to leave again. 

She's always telling me that everything is gonna be fine and that there's nothing to worry about. But she's just very scared that I'm too dependent on her, which I of course think I am. She was that angel that took me away from this toxic place and took me under her wing, cared for me and introduced me to her friends. I've never experienced how it's like to have friends until I met hers. I've never been more active and happy in my life. I've started doing things I like because of her; gardening, walking, and a bunch more things. 

I don't feel like I can take any of this. This Monday she is gonna leave to go back and I know very well how I'm going to react to her leaving. I just feel so useless knowing that I have ruined my entire life; no job experience, no degrees, no diplomas, I stopped school because it felt too much for me, I have no real life friends here and I can't fall back upon anything but her. I don't deserve her. 

I keep thinking that because of my behaviour she might leave me, even though she told me she won't, I feel like she might. I've just always been so shielded from reality that now, in one swoop I have to do all of this (I should also mention I have mild autism, which makes it extremely hard for me to endure big changes in my life that can impact me negatively).

I've been really thinking about all of this, and I also need to say that I believe my mom (I don't have a dad) has had a big impact on me and my behaviour, my past and.. yeah, she just really isn't there for me, she never really pushed me into the right direction or showed any form of care and interest in my future, she just let me sit in my room for most of my life and simply rot away playing video games. She's always way too easy on me that if I say no, she accepts it. 

This post has already gotten way too long than I wanted it to be, I'd like to apologise if this isn't the right place or topic for me to post this. And I'm sorry if my problems might sound like I'm being rude to others. 

Thank you.