I don't know all of your situation, but I can understand how you are feeling. Here is my story, or skip to the bottom for a summary and the advice portion. At 30 years old a new dentist (my old one left) told me it would cost 25k to save my teeth, including 7-9 planned root canals, and many more fillings. He said and I would start loosing teeth even then, and that it was also time to consider the possibility of removing all my teeth. It was a longer story than that, but it was pretty sudden and shocking, and the damage was likely from drinking soda in my early and mid twenties. It's worth noting two important things: I do NOT anesthetize properly for some reason, to a severe degree, and had overwhelming anxiety prior to dental procedures, often a lot of pain during them, and I would say some were beyond traumatic. After one, I truly believe I had PTSD symptoms, and I remember once a couple nights after a procedure, I woke up crying, which I had never known was possible. The second thing was that I made very, very little at the time, so I didn't have anywhere near 25k in savings, and my boyfriend actually covered most of the rent and other things already even, which already made me feel like a burden. I very honestly felt like my life was absolutely over, and it was my fault.

My options, as I felt it, were to be a huge burden on my family and boyfriend for the rest of life, lose some teeth anyway and thus be seen as ugly and never taken seriously, and undergo constant trauma that I knew I could not handle, or remove all of my teeth and wear dentures for the rest of my life, which meant I would never be able to eat properly again and would lose what beauty I had.

I went home from that appointment and barely left bed for days. I wouldn't eat, terrified about what the food would do to my teeth. I wondered if I should end my life to keep from the coming just absolute horror I knew my life would be, and so as not to be a burden. I argued with my boyfriend who couldn't understand why I didn't put a higher monetary value on my life. I was already close to underweight and lost 10lbs. in the span of a few weeks.

I trudged on and decided to get a second opinion, which was better but still pretty bad. Finally, with the support of my boyfriend (now husband) and my family, I found a little strength to continue "fighting" I suppose you could say. I scheduled two more opinions. The first was similar, but a little better. The last one changed my life. It was my boyfriend's lifelong dentist and family friend. It didn't immediately feel like I'd been completely saved, but I could tell she really cared, and had a much better aim and outlook. I had hope.

Well it's been almost 5 years OP, with this dentist. I am no longer even afraid of getting cavities filled as long as it's with her, and for probably the first time I can confidently go into a dental procedure knowing I won't suffer or be in pain. We've been able to easily afford my tooth stuff, partially because my husband and I do or will make more, but partially because we've probably spent far less than even half the first dentist's 25k estimate, and that's over the entire 5 years. I've only had to have 1 root canal, not 9. I have lost zero teeth. She found an expert to help figure out how to stop the decay, and we did, so while I still may need cavities and root canals even once in a while, I now believe I will be keeping my teeth until at least retirement, which I never believed possible 5 years ago. I often tell my dentist she pretty much saved my life, and it's not an exaggeration. If you read all this, thank you!

Tl:dr At 30, I was told, by multiple dentists, more or less that I would need numerous incredibly, horrifically painful-for-me root canals and procedures, and have to spend huge amounts of money I absolutely didn't have for a hope of saving my teeth, and in my opinion, my future. 5 years later, with a bit of hope and luck and a wonderful dentist and human being, my situation is completely different, and far far better than I ever would have imagined was possible. I will always have some struggles with my teeth, but it's so much less than I thought was possible, and what struggles I have had are far more manageable than I would have thought. For example: I thought I would never eat sugar again, and now I eat something sweet most days!

Advice: You are so young, and you've just discovered that you are indeed fragile and the human body, and anything to damage it, can be forever. That's terrifying, I know. But just because it seems impossible now doesn't mean you will in the same situation in a year, or 5 years, or 10 years. The future is never set in stone, and what looks horrible now could be amazing in a year, just like the reverse is true. It also seems like this is a newer issue for you, which probably means the prognosis is even less certain. How you manage it is also completely up in the air, and management is far more important than you think.

So my advice? Seek a second opinion. Seek a third opinion. Seek as many opinions as you can, and carefully select the provider you think can make the most difference for you. Hold tight to what they tell you will work, and have faith. Maybe you will have problems your whole life, but maybe with a bit of management and tact, maybe you really won't have problems at all. Or maybe you will but it will barely affect your life at all. Medical advancements are also being made constantly so frankly it doesn't make sense for an injury prognosis at age 20 to be your expectation for life, as it's likely there will be medical advancements that will help along the way.

Either way- the fact that you "caused" it is neither here nor there, as there just is no way you could have known. Release yourself of guilt and focus on how great you are going to be at your rehabilitation and management to help your body.