I'm sorry about your mom's illness.
What I'm reading here in this thread is that you haven't found the right therapist yet. And us jokers on the internet cannot fill that void for you.
We all have to live with bad memories. Regardless of quality if we were to enter a pissing contest to see whose suffering is greatest. You're not living with yours, they keep you as a pet. I would go so far as saying being an obsessive goodie has not worked for you either. So look for a different therapist. At the very least another channel for you pent up regret. You can of course still be nice to the people around you. But you gotta give yourself a break from trying to outshine your average saint.
When you're using lemmy or mastodon, you don't have to use the website. You can use an app that goes from your fingers to the server without needing a browser and a website to exchange the information.
So most if not all the instances of the fediverse are also a website if you need to use it. But not every website is an instance of the fediverse.