i understand that, feeling underrated and not confident in what you do etc. I go to group therapy to help with anxiety, learn some strategies to help feel better... I wonder if there is anything like that you can try to look for within your community? Then again DS is a good community, to not feel alone and get support. keep reaching out here, whenever you need it =)
sorry your feeling this way, take it a day at a time, your not alone.

You could be burnt out. It happened to me. 30 years at the same company doing a couple of different jobs and I had just had it. The politics, back stabbing, down sizing etc. Had to retire to change and move on. Now I work part time. Yes, there are some issues at the new place too. But I'm not any where near burnt out. Try some changes in your life if you can. It isn't easy. Maybe a hobby or part time work. You need something to add some spark. Just being around new people has helped me. Best of luck

Writing it out is the most important first step!

Twenty years, you've changed along with the work place, so take the time to put to paper all those "little" tasks that you accomplished over the years to reach where you are now.

You can be in a room full of people and still feel lonely. Being alone can be golden.

Use positive images and words to help you connect to the feelings to give you a better balance.

Being alone, you can choose what you want to do with your daily activities. Check out new places, talk to people, smile, and enjoy your adventures.

To help bring lonely feeling to a normal place, work on reaching out to someone who you can help just by being there. Or go help at an animal shelter. Helping others will give you a focus in the moment.

Best wishes. You are not alone, and you are stronger than you realize.

I can relate, I too had been in a job for years and thought I seen and done it all. I was loosing patience in my coworkers and customers and felt as if I couldn't do it anymore. I felt at a stand still and didn't know how to connect to others, so I just bottled up. I kept up the required, do my part, to get a check but something had to change. When I felt as if it was everyone else's fault, I stopped and reevaluated what I wanted in life. Just like others have commented, you have to try something new. I sort of made a couple different lists: daily/weekly goals, goals to accomplish by the end of the year, three year goals and on up to that "bucket list". Some are written down, others just pictures. I started small so I could make my short term goals and feel as if I accomplished something for the day/week, That way I could have momentum and confidence in myself that I would one day reach my long term goals. Nothing is fixed overnight, it took you a long time to get to this point so don't force yourself to say "I should feel better by now", but do appreciate the small moments and build off that. Then periodically, you can look back and see that you are feeling better than you did.

I'm so sorry you feel overwhelmed. Please remember you are not alone. We all feel overwhelmed and lonely at times. I am glad you decided to share. This is a safe place.