I feel exactly the same way. I recently separated from my partner and moved out, he was the only person I really ever spoke with. I always said he was my best friend (even though looking back, he was an ass to me at times). I literally don't have anyone, I don't speak to the majority of my family anymore and the only family I do speak to all live quite far. The two people I would call friends also live in other cities, I don't see them often at all. One of them I've not seen in about 3 years.
I see people through work (just co-workers and I'm older than most of them! They're all about 18-21) and my kids, I try to get out as much as I can with them (they're 3 and 11 months) to library, music time, story time etc. But I tend not to socialise to much at those as I'm so bloody socially awkward! Cliques form even at those library events and it's hard to get 'in' with people.
It is hard so I completely relate. Every day is the same: work, kids, housework, sleep & repeat.