Do you have any hobbies? There's always meet up groups online, maybe you can see if there's something in your area to go to and make new friends. Also I know how hard it can be when friends either up and leave or slowly fade away because of their own lives. Its rough but its inevitable for everyone. I hope things get better for you.

I don't necessarily have any suggestions but I do empathize with how you feel. After my last serious relationship I have been too afraid to trust anyone enough to be with them. My friends are almost non existent as well. The ones I do have I only text, I haven't actually seen them in months and months. Since I started a new job I have found some new friendships and that has helped a lot, but I also don't tend to trust that they won't leave.

Just know you're not alone in feeling alone.

you are not alone many of us are in the same boat please don't give up I used to be a teacher and got disgraced when I told them I had mental health challenges

It seems you've come to the end of the leeway you've given yourself so it might be time for medication, or serious counselling or something. You need to be channelled into social groups to meet people and be forced in with them over a period of time. If you aren't contributing you need to learn how to contribute... in short you're going to have to take this bull by the horns, figure out what you're not doing, and start doing it even though it takes you out of your comfort zone and possibly gives you anxiety attacks.

You don't have to be alone. You can come back from this, but it won't be comfortable. It will be entirely worth it, but it won't be comfortable. Are you ready?

Yeah it's true, never admit it to an employer unless they ask. About five/six years ago an employer asked about my mental heath after a relative died. I was up front about it but do I regret that. Better to keep them guessing. I am a teacher also.