I am single and childless OP, mine is a long term situation and I am at peace with it, but even I still experience the crushing loneliness it sounds like you are feeling.
Exercise is so important to well-being so do try and do something active. I started doing fitness classes, even though I hadn't enjoyed them before, but I got as much out of them for the human contact as the exercise. You get to know the regulars and just that little chat and a joke is a lift.
Take pride in your surroundings. It's easy to let things domestic stuff slide but having a nice environment, made nice by you and for you, can be soothing.
Volunteering at parkrun is a great way to start the weekend if it's stretching out ahead of you like a void. There's human interaction, and if you make yourself cheer people on, you can't help but feel brighter yourself.
Make plans for weekends away. Having something to look forward to is important, and breaks up a 'run' of weekends. Spending time planning the itinerary is fun too.
Good luck and carpe diem OP!