Thank you for sharing your experience!
> how were they negatively impacting your mental wellbeing?
I think the answer to your question is obviously very personal and will change from an individual to another.
For me personally the stress came in 2 forms:
* Outrage/politics, especially on Twitter and Reddit. On Twitter, it's impossible to escape this, even if you carefully sanitise the list of those who you follow, due to the trending section being visible to everyone. On Reddit, if you visit the site while you are not logged in, again you will see all of the above.
* Time sink. The worst offender here was Youtube. E.g. "I need to do X in my aquarium let me just quickly double check that video by Aquarium Co-op" - 2 hours later (spent watching "recommended next" videos) I would realise "wow I just wasted 2 hours of my life". Note that I can still quickly view a video without having an account, but due to not having followlists and such, the recommendations are less addictive. Facebook and Instagram were also a time sink and unlike Youtube they weren't really useful in any obvious way, except maybe a couple of Facebook Groups I was part of (e.g. my daughter's school parents group where I could get some news about the school - I now subscribe to their newsletter instead).
* Instigating compulsive spending, e.g. Amazon - this is quite obvious due to it being an e-commerce website and knowing well what you're thinking to buy. I now shop on local retailers whenever possible and as a last resort on eBay, since at least it is less pervasive - unlike Amazon which entices you to take advantage of the rest of their ecosystem e.g. Prime Video or Kindle or Twitch, then "follows" you in all those places with tracking ads.
> Google Search is by far the best, IMO, and saves me hours every day.
If you use Duckduckgo, you can add !sp at the end of your search, and you will get proxied Google results. You don't need to have a Google account for that.
> I have my personal domain go to gmail, and it makes managing ages of email a breeze.
Having a personal domain is a great first step, well done! I didn't have it so I had to setup an "out of office" message, warning everyone that my Gmail address would be deactivated soon...