Suspected malware after installing FileZilla. How much trouble am I in?

Hey all - I'm trying to help myself as much as possible, and I've been doing a lot of reading, but please accept my apologies if I missed something obvious.

Computer: iMac Pro, running 10.13.3

SITUATION:


Opened Chrome (which I do not usually use) and received a warning that an extension called "Search Manager 10.1.2.64" is trying to set my default search bar to srchbar.com

Did some digging and found the extension was installed about a week ago, right after I installed FileZilla.

Did some more digging, and found "runChmm" in my login items, also installed at the same time. I haven't restarted since this, so hadn't encountered it yet. This launches something called Chromium that I never installed, which defaults to what seems to be a sketchy knockoff of Yahoo search.


I've noticed Safari lagging like crazy when typing in the URL box, and now I wonder if this is related.

No extensions show as installed in Safari.

Currently running BitDefender.

Ran MalwareBytes and it came up clean.

QUESTIONS:

• How freaked out should I be?

• Do I need to wipe my system drive?

• Reinstall OS?

• Wipe other stuff? Like, can my personal files be infected?

• Can I trust my Time Machine backup from before the date in question or could that be compromised too, so restoring from it just reinfects me?

• Do I need to worry that passwords and personal data stored on my machine are compromised?

• Is there a way to know for sure what happened, and what else is installed?

THANKS SO MUCH!