I'm 24 and I feel so burnt out and overwhelmed with life right now

I'm 24f and it has been a really exhausting year. First my grandma that I was very close with passed away. My parents worked a lot when I was growing up and she basically raised me. I miss her everyday and I thought it would have gotten easier by now but it hasn't. Then I lost my job that I've been working at for over 3 years. The company I work for ended up in some financial trouble and they had to let me and bunch of other people go.

I applied to a lot of companies but I only got an offer from a small startup company. I took the job because I was desperate and needed the money. I am absolutely miserable here. I am so greatful that I have a job but it is so stressful. I'm over worked and underpaid. They are serverly understaffed and most of the workload falls on me. I have no support at this job and I have been working from 8 a.m. to 8 p.m. almost every day now sometimes even later. I am also doing my master's degree. I'm in the middle of finals right not and I'm having a really had time balancing both work and school.

I spend at least an hour every day applying to new jobs but I haven't had any luck yet. I would spend hours updating my resume to best match each job description and writing personal cover letters for each job but I've gotten ghosted by almost every job I've applied to. I wish these companies would acknowledge me in some way. Even if it's a rejection because that would be much better than being ghosted. The one job offer I got was rescinded because they decided to go with someone else after actually offering me the job. On top of everything I'm have a lot of personal family issues that I've been dealing with lately. Everyone basically uses me as their therapist and it's exhausting.

I don’t think I've ever felt so burnt out in my entire life. I'm so mentally and physically exhausted. I feel like my brain isn't working properly right now. I was even struggling to write a simple email earlier today and I couldn't get my brain to focus. My job is the thing that has been stressing me out the most but it's what I have for now so I just have to deal with it. I am trying my best right now but I don't know how much longer I am going to last.