Wow. 😱
Your major issue is a hard drive that is just barely working:
Performance:
System Load: 1.51 (1 min ago) 1.54 (5 min ago) 1.47 (15 min ago)
Nominal I/O usage: 0.36 MB/s
File system: 139.13 seconds (timed out)
Write speed: 1 MB/s
Read speed: 1 MB/s
You've set a new record! That is the worst I've ever seen in reviewing thousands of EtreCheck reports from barely working Macs. Your write /read speeds should be in the 70-80MB/sec range even for the slow factory HD you have. I have the very same model but upgraded to an inexpensive solid-state drive (SSD) and it now does ~500MB/sec and "feels" very fast.
Normally that awful level of performance would call for a new drive, an easy at-home project in that model. However, that model has a little "quirk" that can trick people into changing a drive that is not broken—the hard drive cable.
The cable in that model is super-thin and its insulation thinner. After 3-5 years of vibration from normal use and transport, the cable can chafe against sharp metal edges on the computer chassis and lose some insulation. There is an entire litany of oddball symptoms that a worn cable can cause, include extreme write/read slowness.
Were the computer working better, I'd have you clean out the useless software you've installed first. but that does not sound feasible in your case. Install a new cable first. They are available, cheap, and an easy 20-30 minute at-home install. I get mine here:
Apple Hard Drive / SSD Cable For 13-inch MacBook Pro (Mid 2012) main drive bay
If that fails to make a difference, and assuming you want to keep the computer, then we replace the drive using the new cable.
It is your call if you want to replace and or upgrade the drive. A new drive "kit" with a 500GB SSD, tools, and a nearly must-have date transfer case costs around US$100. The computer is still not on Apple "vintage" list and was the last Macbook Pro with an optical drive. However, it maxes out tje OS at 10.15 If you hope to get additional and more enjoyable service from this computer, the SSD option will do it. If not. it's time to replace.
Regardless you need do do some take-no-prisoners housekeeping if and when the speed issue improves. I would not start with housekeeping with the world's slowest hard drive at 1MB/sec.
1) Use MalwareBytes (get only from the developer's site: https://www.malwarebytes.com/mac ) to get rid of your adware infection.
2) Using the developers' instructions, remove the VPN—client-side VPNs are basically useless— and Total AV. You have a Mac—treat it like one!
If you are interested in the SSD option, post back for links to parts and video instructions. Most of us recommend only the Crucial MX series or the OWC Electra 6G for this conversion in Macs. Post back, but do the cable swap FIRST.
Comment: I am currently tied up in recovery from total knee replacement surgery and have limited access to my computer desk and my 2017 iMac 5K i7. My 2012 MBP13 is giving most excellent service as I have to work from some very odd position required for healing.