That sounds like a severe case of "ADHD paralysis". I never experienced it so strongly, but I know the feeling when you want to do something but can't force yourself to stand up and actually do it. If this is purely ADHD related, then it is what is called executive dysfunction, because of (most likely) a lack of dopamine available in the brain. That's where the right medication can help. Never had this "paralysis" again since I got them.
But you're also talking about sadness. I thought I had depressive episodes, but it turns out in my case it was all just secondary to living with ADHD. However some people develop serious depression and/or anxiety issues.
Did you get professionally evaluated and diagnosed? If not, you really, really should. It was the first step on my path of fixing these issues.
I said only you know yourself best, but depending on how bad it is, sometimes the best you can do for yourself is get some help to get you out of the "black hole" first. Your case does sound pretty serious, so you maybe should not try to fix it all on your own. At some point I accepted that I need some help, because I did not know what to do (and did not really know what was "broken" back then).
My diagnosis is now more than 2 years ago, I have been struggling in certain ways all my life, and some problems will never go away, but feeling inadequate, sad and paralyzed - I only remember this like a dim nightmare from the past. Don't give up, there is hope - it can get better!
I'm just a random guy on the internet, but a doctor with experience in ADHD diagnosis and treatment can help you get access to the support you need.
Woah. If all what you say is true (your account is just one day old and you might be an internet troll for all I know, but if you were, I should not reply further, so if I reply, I have to assume that you are serious, but maybe it's just me being paranoid), then I'm sorry to hear how life has been so far for you.
I don't know how old you are, I would guess between 15 and 20, as it's sounding like school is or was not too many years ago for you (and you are not a native English speaker, are you?)
"Not knowing the definition of a friend" sounds like a familiar thing to me from when I grew up. Teenage/very young adult times were the WORST times of my life. If I guessed your age roughly right, then - good news! Life only gets better from now on !
I had similar experience of not belonging properly to any group in my class back in school and being the weird one who is not avoided like the "outsiders", but also not fitting anywhere properly. This also seems to be a common ADHD experience.
Well, after school you are free to choose your own path - and on the path you tend to find more people like yourself, with similar interests, and more open minded people, with different quirks. Some of them might eventually become friends. People who peaked in school are the true boring losers!
Either you are someone pushed into being socially an introvert by circumstances, or you might also have some autistic traits. ADHD and some form of autism often come together. You might want to research into that. Just had to mention this as a possibility.
If that does not apply to you, then in general - social cues are learnable, if it was just due to missed opportunity. I think I learned to "read" people and behavior of others pretty well, but was very insecure and inadequate as a teenager. It's a matter of practice and self-confidence (which is also learnable, and it grows as you find your self-worth with increasing positive interactions with others and successes in life).
You should definitely not wait with therapy as long as you say you will, and do it once you have the opportunity. You seem to have a lot to unpack. And you SHOULD. You need to process all that crap and talk to other people. At the very least, the therapist can be like a paid friend. In the best case, they are actually good at their job and can do more than just listen and validate you and give you opinions, but also help you navigate your problems and difficulties better and try fixing them. Finding friends is a thing that just happens eventually and you can't force, but finding a therapist is in your hands. If you are in a civilized country where you don't have to pay it yourself - just go for it !
Also, you should check out /r/ADHD on Reddit, it's a huge community (I wish there was more here on Lemmy, well I'm trying my best to make this a good place too, e.g. by replying), there you can see so many people sharing similar struggles, and exchanging ideas and celebrating successes. It was nice to find my "flock" and feel validated and understood. And others could give much better advice than I could, or provide more perspectives. I'm just one random dude you opened up a little to (I might also give bad advice, who knows).
The ADHD community on Mastodon is also pretty friendly and active, so you can go and try hanging there with the people!