Someone hacked me. How did that happened? Am I safe already?

Here's my full story:

It all started yesterday night.

I use two e-mails, one for more buisness and work side, secondary account is more about some shitty games, newsletters etc(cause that account had been hacked a long time ago and i have like 50 login attemps every day, but they're all unsuccesful cause of double authentication).

Someone stolen all of my LoL account by firstly asking for their names on LoL page( i got an email with all of the nicks paired with my e-mail) then one by one their e-mails had been changed(every account was paired with spare e-mail, i also had recived mails about it), then i guess someone changed all of the passwords when e- mails were already changed and that's why i don't have any mails confirming password changes.

On this same e-mail i also had recived LinkedIn PIN's for password changes. I don't know if someone who did it succed to change that password, cause i don't really use LinkedIn acc paired with that e-mail, so i'll just let it be. My account was blocked anyways due to sus activity so no harm here.

But here's the part that i care about MUCH more

today, i recived mail notification on my primary e-mail account that someone just added another e-mail to my Facebook account, and i bet he added that mail to use it to reset my password. I was here so i instantly clicked the notification, then changed my FB password then this just happened again! I got so stressed so i changed my password again and scrolled through all security settings possible on Facebook, and i noticed that i had about 80 "trusted devices" and all of them were added in exact same time (these devices doesn't require to get double authentication code to log-in). I could see localization and type of each of the device, and they were mainly from my country, but i also had some from USA and Germany. I manually deleted each of the devices including mine too.

I also noticed on my account that someone added application to generate log-in codes to my account(it wasn't 100% me). I mean app like Google Authorization. I have also deleted that app from my account and everything since then seems to be good, but i don't know if that's really the end...

I was thinking my ass of how is that possible for someone to do these kind of things WITHOUT even logging to my facebook acc? Like how can someone add e-mail to my account without logging on that account? I'm literally scared to death to do anything anymore? I'm also not sure about how i catch this shit, yesterday i've been looking for some old ass game to download and i clicked wrong "download" button, so i think it was that thing, cause when i opened something that should be installation wizard, two command prompts popped up. That's when i got scared as shit, closed these in Task manager, restarted my PC and i ran ESET Online Scanner, but it didn't catch anything... so i'm not really sure about that

So, here's my story, i hope someone will read it and give me some advices what can i do now and answer me how it's possible to do something on Facebook account without logging on it.

Oh, my dumb ass almost forgot to say- i already formatted my PC and i did hard reset on my Android phone too