Sounds like seasonal depression. I struggle with it and winter is hell for me too. Plus, winter is cuffing season and everyone wants a relationship. Most of my friends are dating and I broke up with my bf recently so I’ve been having similar miserable thoughts of worthlessness, etc. It helps me to just “ride the wave.” Nights are worst for me, so I kind of let myself melt into sad songs on long drives alone at night. I know when I wake up and it’s morning I’ll feel a little better and hold on to that. I wake up, make a cup of tea, go to work/class and try to find joy in the little things I can control (like making tea and snuggling up to a good show). I remind myself that it’ll all pass and I’ll feel better when it’s warm again. I’m a stdent and my Uni offers free therapy so I talk to a therapist too. When I feel really sucidal, I make sure I’m never alone. I’m sorry you struggle with that too and my remedies may not help you, but I hope they might be able to at least a bit.