Yeah, I also became a bit like that after my surgery.
Not a "I'm going to complaint about my problems here too" post, just my experiences, you might feel identified and that always helps a little.
Everything possibly going wrong went wrong. The system just trying to dodge all your complaints and doing nothing.
Then people you thought you knew and considered good friends, only calling when
their crappy device broke down or having problems with
their live/job/family/girlfriend/wife, totally selfish, but otherwise, knowing you were spending weeks alone at home, barely able to move, not a single call asking how it was going, basically giving zero f**.
Since then I dumped all the trash out and kept only the valueable ones, not looking forward, that's not selfish, but self-care.
All that people sending a message once every 6 months like
- "Hey how it's going? Well? nice!" (Introduction)
- "Erm... could you check this for me? It's not working" (Real purpose)
- "Huh? Sorry, I'm busy" (Scratching my balls), "Could you ask in a few days?"
- Days Later: "Sorry, still busy..." And so on, they eventually get it
The main issue is you little to no patience with idiots, right?
Can't see the problem. Idiots become like that because nobody puts'em in their place ever.
I have less friends now, but true friends, not convenience bastards haha.
And yeah, I can also relate with "Why keep breathing? What's the benefit?" feeling.
Comes in and goes out, try to force yourself on doing some activity, usually helps.
For example I always found weight lifting relaxing
The subsequent muscular stiffness hurts a little, but I kinda like it, shows you did something.
And those two days after I feel like on a morphine shot or something, must be all the serotonin production

No problem about saying things out anymore. Recently I fixed a 180€ car part for a friend with a $3 motor.
When I went to ship it back, he argued the shipping company I was choosing costed 2€ more than other one placed at the other of the city.
Said some things lol. The hell you want me to spend 20 minutes driving for you saving 2€? Next time buy a new part you f**cunt lol.
Still in a friendly way, but clear!
Just don't keep it all inside. These people aren't keeping it either!