@PhilippaC, my heart goes out to you, and my hat is off to you. You are not alone in experiencing the "postoperative existential crisis" that can really hit those who are recovering alone.
I had THR (left hip, posterior) on Oct 19, 2022. I was sent home about 3 hours after surgery. I was fortunate in that my sister came in from the midwest to help me care for my animals and with the chores I could not do by myself. I also had friends drop by with the customary casseroles and good wishes.
Things were proceeding well... until Day 10 when the support officially stopped.
Of course, it never occurred to me that my friends or family would stop their lives to care for me for a month. I expected to be alone on Day 10. And yet I wasn't emotionally prepared for the thoughts that postop blues can bring up for singles.
For me, what was triggered was not just worry over breaking protocol or dislocation or simply not being able to survive recovery on my own. Instead I spiralled into some hell-narrative about permanent disability -- and worse -- aging. If I fell, whose arms would help me get up? If I screamed, who would know? I chose not to remarry after my divorce, so I began thinking: maybe I should have hung in so my spouse would help me to the bathroom.

I never wanted children, but maybe I should have bitten the bullet so they could clean my kitchen now.
Fortunately, I quickly got over that narcissistic thinking, but I still felt small in the universe and imprisoned in my home, unseen and terribly vulnerable. I'm outgoing and sociable and volunteer in my community. But now all I could see was a very old woman...forgotten and dying alone. It was terrifying, and I cried for two days and nights. How many weeks would pass until they found my body? Would my animals starve or... eat my corpse?????? I'm serious -- I thought these things.
Until I did what you've done. I posted on bonesmart about my depression and received sympathy and reassurance. I no longer felt alone. And if you keep reaching out to us, you may not either, I hope.
The bonesmarters' help provided me the clarity I needed to get practical on my own. For example, I made a list of what I might do in the future if I'm ever in a similar situation. (My other hip isn't great, and both knees have been bad since my fifties, so it's very possible I will experience this again.) I learned that as someone on Medicare and a Supplement, I might travel closer to my sister for surgery and go to a rehab center near her home if that's called for. It wouldn't involve all that travel for her, and it she wouldn't have to be on call 24/7. It would also provide me with proper postop care should I need it.
I'm not sure what your insurer will allow if you should find yourself overwhelmed again by being alone after surgery. But the fact is that it can be very overwhelming to recover from posterior thr alone, and you are going through a very common experience for many of us who are or have been in your situation. So PLEASE feel free to vent here. We get it! But do research rehab center possibilities should you ever need surgery again.
As for now, can you arrange for some at-home care? I'm not sure how you feel about admitting your feelings to your family or friends...but might they take turns dropping by for a bit each day for some help and cheering up?
One piece of helpful advice you'll get here for physical pain is "ice, ice, ice." I found that to ward off my postop existential angst as a single, I needed to "distract, distract, distract." I binge-watched comedies, talked long-distance with friends, and read. I even ordered flowers for myself and had them delivered!
My battery is running low, so I'll post this now and write another in a bit with some practical tips on doing tasks on your own.

Take care!!!