Oh god, to be fair this sounds like me. I have friends, but I'm really pretty much a loner (YES JACK A LONER CABAL) and my best friend legitimately is my husband, my mum and my brother. I'm friends with my husband's friends and their wives but really, I don't have anyone I'm super close that is independent of either family or my husband.
I've always been like it, even at school I preferred my brother's company (not in a weird way) and being within my family. My other friend who I guess I'd term as 'best' is my ex, as he's super cool (we were just like brother and sister in the end though). I'm not a really good socialiser and tbh, kinda hate it.
That said, if me and my husband broke up, his friends would still look out for me, unless I did something unbearably cunty (unlikely)