that sounds difficult and even scary to deal with. youre a strong person to get through that and im glad your at your moms right now to collect your thoughts. suicide isnt just about feeling sad. You can feel the rush suddenly even when there isnt necessarily a reason. and therefore dont blame yourself for not being good enough or figuring yourself out, this is beyond will power! a good thing to realize is youre not at fault if you feel depressed, in fact everytime u go through it your brain is sort of paveing that pathway making it easier next time, so talk to a doctor and say youre having trouble controlling your emotions. think of that as a medical thing, not a personal failure! and anything you can do to prevent it is great
as for the things that really have made you sad and possibly started this cycle, the end of relationships and being lonely, what are some ideas you have for repairing those parts of your life? do you have any ideas or goals to think about? Making a plan for yourself, even if its just a plan for how youre going to stay focused tomorrow, that is so good!
you can do this, you need to get some clarity but i think you can do this and i dont want you to do it alone so thats why i recommend a therapist or doctor just to help rewire ur brain a bit

i dont know if thats helpful or comforting, i dont think you should blame yourself, i can tell from reading your post that some things broke you down and that kept getting fed, but you can also feed the part of you that fights to stay bright and your going to see that grow