Advice - difficult lab situation probably already added a year to my time to graduate

TLDR - PI is finally doing what she needs to on her end, but I am still stuck not making progress because a difficult lab member trained me to do everything wrong (at least one major step per experiment was taught to me wrong). Can't fire him, he will confront me if it gets around I tried to go to HR. He will not stop trying to "fix" and "help and meddle WHILE I'm working.

PhD program - science field.

There was one red flag when I rotated in the lab. The senior scientist was kinda a sexist ass. He always wants to help and fix things, always is in everyone's business even if they aren't in our lab, and spoke down to me a lot. During my masters I had a lab mate who was always in a bad mood, but once I got my project running and knew where everything was, I just had to interact with my PI once a week or whenever I had questions, and all was well. So I joined this lab anyway because I really liked the research and my PI.

My PI was a little too hands off in the lab, something she has recently changed. The senior scientist wasn't keeping a regular lab notebook, and was always very defensive when asked to write things down and show her. He felt like she was singling him out because he was the only man, and she wanted to micromanage him. He can't take responsibility for any mistakes he makes, always tries to shift the blame. There have been SO MANY PROBLEMS in the past year with him, experiments they had to redo because he wasn't doing them correctly. It has been WILD.

But my issue is that he interferes with me becoming independent. When I rotated and first started in the lab, he was in charge of training me. He would hand me the exact volume of solutions I would need so I wouldn't make mistakes or contaminate things. Mostly, I just watched him do things and took notes on how he did them. This August, I finally officially started doing lab work. I worked more with my PI, and every experiment we would find something major that he told me to do incorrectly. When this would come out, he would turn it back on me, asking me why I didn't feel like I could come to him if I was confused. I always did my math with him before an experiment, so if I was confused, then I was somehow mishearing every single number that we checked. Even though my PI has taken over working with me, he still stands over me when she isn't around and tries to get me to do things his way. If I say no, he just comes back after a minute or so and tries again. I've been struggling with cell culture and last Friday we finally found out why. He told me to do things a completely different way than he did it. He want's to "reteach" me but I keep telling him I'm waiting for my PI but he won't stop or go away.

My PI is also trying to fire him because of the issues with his not having a lab notebook for so long, all the costly mistakes she uncovered, he won't take responsibility for mistakes, and he's a general pain to work with. Because she has tenure, she has to go through this 100 step process through HR. He said he would sue her for discriminating against him as a man.

I just want him to get the fuck outta here. It's my PI's fault she let this go on for so long before taking action, she should have been more present, and made sure proper records were always kept. But here we are. I can't continue working like this. If I take action and he finds out, he will confront me, and make me super uncomfortable. I would 100% have an anxiety attack and want to avoid work at all costs. Since he is here all day I can't really avoid him. I have been in this lab for a whole year and learned nothing. Last year I was taking classes and shadowing, doing an experiment here and there. Just telling myself when classes are over I will get in lab and start doing all the experiments I've been dying to do, spending a quiet weekend here and there listening to podcasts and pipetting. I have learned absolutely nothing correctly.

I just don't know what to do but at the end of the day I need to move forward so I can graduate. Advice???