Hello! I started job searching just as the pandemic set in last year. I was in a similar situation where the relationship with my manager at old job was deteriorating in a way that I also described as "familiarity breeds contempt." I don't think I had slept through the night in 2 full years, the gaslighting that went on there had me questioning my own sanity and self-worth, and on top of that the pandemic hit just as I made up my mind to get out. It was hard to job search in that frame of mind, but I just kept plugging away at it with a goal of doing something to advance the search, however little, every day.
It took me 8 months to find a new position, and it was essentially like having a part-time job on top of the full-time job. I second the website askamanager.org--it's amazing. I also ended up paying a service a couple hundred bucks to re-write my resume and linkedin profile, just because my resume was 20 years old and I felt like I needed a second, neutral opinion. I reached out to a recruiter, friends and former colleagues to tell them I was looking. I practiced answering interview questions with my husband and a couple of friends to fine-tune my wording and get feedback. The first interview was still awful, but they got better! The cover letters became easier to write and the interviews went more smoothly each time.
Other tips I have based on my involvement in hiring staff at various times: HR will definitely do a search and go through your FB profile and anything else they can find. If applicable, be sure to follow any directions in the job listing and not just send a resume; at old job and new job, any applicants who don't follow all instructions are immediately thrown out (like "send us a cover letter, resume, and answer the question "why do you want to work here"--people who didn't answer the question were out).
Good luck to you and I hope you find a great position!