I am currently considering if I should I tell my new boss I don't think I'm a good fit for my new position?

I have nothing else lined up at this point, but I feel as if I can't survive. I've been dealing with a lot anxiety, and I'm not sure how much longer I'll last at this job.

Some background Info I recently left the IT field I was in for the last 3 years due to stress and boredom. I was working for my local University as an IT support specialist and was working remotely up until this spring started. Dreading the long commute and stresses that come with working in a city I decided to change careers into Technical Writing as I thought my skills would transfer over well.

Current job pays well, has good benefits and allows me to work from home. My manager recently threw me into my first project alone and I have been struggling to meet the deadlines for the past 2 weeks. It sucks because everyone I work with seems so nice but there are so many things I don't understand and am struggling to keep up with procedures, formatting, and deadlines with others.

I was unemployed for 4 months as I quit my last job with nothing lined up back in July and while it was nice at first I felt so worthless not having a job.

I have a 2 week break coming up thus week for the holidays so I would be deciding what to do by then.

Any advice would be greatly appreciated.