Help! I got hacked after Whistleblowing (MITM attack)

Hi, if anyone could help me with securing my devices I would appreciate it immensely. Here's a quick rundown of what's been going on:

I blew the whistle at work re. toxic work environment and I experienced severe retaliation from my managers, workplace hostility and professional sabotage as a result. One manager (with a cybersecurity/hacking background) showed an unusual interest in me and often brought up in conversation that they used tools like Kali Linux. I am out of my depth when it comes to cybersecurity, generally

Due to how rough conditions in the workplace became, I have had to work remotely for months, frequently using public wifi. A few months ago I noticed strange & unfamiliar programmes in my MacBook downloads, some with system-level access, that I definitely did not install. I suspect my phone may be compromised too. This is why I suspect this at least started as MITM.

A lot of my confidential information has leaked. It's really unnerving.

Because of the legal sensitivity of my situation, and implications on public spending, there is reason to believe that my information would be valuable enough to target, at this time. My communications, financial info and personal data are extremely sensitive. I’m worried my privacy may be compromised, but I’m not sure where to begin or what to check.

Where should i start if i believe my devices and key accounts may have been compromised? Should I buy a YubiKey?

And what are some best practices to defend myself moving forward? (Beyond using a VPN especially in the case of a very committed and persistent hacker?)

I really need help with at least a better understanding of this.

Thanks so much for anyone who's read this and is able to answer my questions ❤️ i really appreciate it