I am sorry that you feel that way. I can identify with that feeling of extreme loneliness.
One question: when you say ‘taking care of yourself’, do you mean financially or emotionally? My approach, since you asked, is the following: I have two jobs and I end up working about 10 to 12 hours/day. This is significantly more than what the married or livein couples (around me) do.
Physically: i try to workout four to five times a week and it helps with my depression and anxiety. I usually eat pretty healthy and clean (no sugar or food from a box) which help a lot.
Emotionally? I have no idea, really. I write and read a lot. I take long hikes in nature and I volunteer. I listen to podcasts that tell stories of those we know nothing about. I read about philosophy. These activities keep me grounded, humble and sane.
I don’t have any close friends. I moved around a lot, besides all my friends got married and started their new chapters and I never hear from them. I guess, I have gotten to used to being alone as life forced me into it. I know, I crave genuine relationships but I also know that it is very difficult to find and maintain. Most people don’t let others get into their circle. Especially if you are single and an outsider. So, I have been spending my evenings, weekends and holidays alone for as long as I can remember.