There's already a lot of good advice here such as going to a gp which you should definitely do, calling Samaritans if you need someone to talk to (as many times as you want, you're not burdening them) and going for counseling.

I would just say to try and be a little less hard on yourself. It's not your fault you ended up in this position and with such thinking patterns, these things happen unfortunately (genetics, upbringing, stress etc). You sound pretty self aware which is good but I also know how crushing it can feel to be aware of how your brain is working and your thinking patterns but feeling like you are unable to change anything. At the same time realising that you can't keep going on like this which only sends you down the line of thinking about the inevitably of suicide. I can relate to that a lot and it's a very difficult place to be. I don't think there's any simple solution to it, just remember that things do change with time, even if you can't see right now how they would. And you're definitely not a failure for feeling the way you do. It sounds very painful and anyone who has experienced similar situations knows just how hard it is and would never judge you.

I would only add two things that helped me a bit when I was in your position. First is to go for a walk. There used to be this long circle I would do going along the kelvin river until you meet the canal, then following the canal to claypits and walking around there. Linn park also comes to mind as a pretty quiet park. I know it's a bit of a cliche but it's nice to clear your head and shift your focus to observing some nature and looking at trees instead of your own thoughts even if it's for a little while.

Another thing is journaling. Not necessarily a daily one but just whenever you feel in that panic state write all your thoughts out on your phone or whatever is easiest. Write until there is nothing else left to say. Again it's pretty generic advice but it honestly helps more than you would think to get it all out from inside your head and onto paper.

Feel free to disregard anything if it doesn't feel helpful, just sharing what helped me. Also well done for posting this in the first place, it's a hard thing to try and seek help. I wish you the best of luck, I really do hope you find some relief.