What you are going through now, a lot of people have done in their lives. A few weeks ago, due to suffering from severe insomnia, I was starting to have irrational thoughts just like you; "What if even the strongest medication cannot calm me down and send me to sleep?", "What if my anxiety gets so bad that nothing can help me?", "What if I end up in a mental institution", "I may never get a girlfriend or have a family" - all these are common thoughts that I have.
I have also had suicidal thoughts. They are not nice. I think what you are experiencing right now is a severely derealisation episode due to anxiety. You may feel like the world around you is not real - or the world may appear differently to you than what it did before your anxiety. This may be causing you more anxiety feelings. The thought of never being able to overcome it.
You need to understand that thinking that it may never get better, is certainly not a step towards getting better. Try and remind yourself that it will pass. Reading about other peoples experience will help (at least it helped with me). Understand that there are many others out there who are in the exact same boat as you - and there are very likely many more people who are suffering to a greater extent than you.
Honestly, hard times do pass. If they haven't, you are still currently in those hard times. And just because you are still suffering, this does not mean it will never pass. I think you know deep down that these undesirable manifestations are entirely the result of mere thoughts. But as you know, those thoughts can manifest in the craziest ways. This is a good sign. Thinking that you are mental or going mental is actually a sign of sanity. You just need to remember that you will certainly not be like this forever.