I'm sorry to hear this.
I used to have major struggles like this when I was younger. I think people like us are very much in our own heads, maybe too much. Sometimes it's good for us to just jump out there and socialize. Sometimes all it takes is to pretend to be outgoing for 2 hours at a time. Go to a conference for work, or play sports at the gym, whatever. Of course it's a challenge every time, and I'm oversimplifying (I'm definitely no mental health professional). It took me years -- decades really -- to get more comfortable being outgoing. But a life lived with good relationships is truly a more fulfilling life.
Progress in this area often happens by way of other activities, because it's just less initially awkward, and people have things in common. Do you like sports? Join a softball team. Music? Take lessons, and play shows and meet people. Go to the same restaurant regularly and get to know the staff. Volunteer and help others. Join a church or an organization with people that share your beliefs. Have conversations with people you come across -- take interest in the Uber drivers' lives, and you'll quickly become their favorite customer. Once you have good connections with a group of people, before you know it you'll start meeting their friends, and so on, and eventually you'll have your own group of buddies that you'll see around town.
Also, you're connecting with others on Hacker News, which is something. I think you might have more of a knack for this than you realize. I would say to do what you're doing here -- people don't have enough conversations in the real world, so people that do so stand out as being friendly.
It hurts me to hear of other people going through what I went through and still do from time to time. But if I could boil what I've learned down to one piece of advice, I would say, show others that you care about them. They're very likely going through struggles similar to what you are experiencing.
Every person in our lives is a gift, and it's easy for all of us to forget this.
Wishing you the best!