Okay, I may well be overreacting here but please bare with me. I started at this company just over a year ago. There is 3 of us in our department, myself, my manager and a guy that started 6 months prior to me starting.
There's been a few things bugging me from the start which made me want to quit in the past but now I've come to a point where I just can't take it anymore. The problem are both my manager and the other colleague. They are both as bad as each other and kiss each other's asses basically! Firstly, he has access to my work emails(where all my payslips and personal information are also sent to). I asked my manager if he can be denied access as I don't feel comfortable wi and she said 'no, we need him on there in case you're on annual leave'. He monitors and sometimes deletes emails (especially from our manager asking me to do something) in my inbox which result in me then looking stupid saying 'I never got that email' to which she can always prove she sent it to me. There's been a lot of times in the past where he did my job without asking (he picked up tasks from my inbox) and deliberately did them wrong which then was blamed on me as this is my job. Once when I was off on annual leave, he changed something very important on a spreadsheet I was working on which resulted in me uploading it to the wrong place. (I didn't think it was him at first but I then looked at the file and it said 'previously saved by XXX on xx date'. My manager started getting very frustrated with me for all these mistakes that 'I' have been making and when I told her once in private what was going on her response was 'X would never do that, don't lie to me' 
The most recent is that we are all working from
Home and after furlough, he was asked to come back long before me but that was fine with me at the time. I have now found out that our hours are meant to be split equally whereas they are not. He has more while I have less. Also fine. The thing that gets me the most is that he now keeps forwarding me emails from our manager which she sent to him privately asking him to do something. Expect, that something is always my job. She asks him to do MY JOB as if I'm incompetent or something. At this point, I've had enough and want to look for a new job but my issue is that I'm 8 weeks pregnant and therefore no one will employ me 