I'm (was) an only child and can sympathise entirely with the OP. Mum and I always had a very tempestuous relationship. She was very jealous (admitted this but didn't see it as a fault) and thought the world was out to get her. All her friends at church thought she was a lovely lady, not realising how manipulative she was and never, never ever hearing her 'vent her spleen' on them, the family, the world in general. As she got older and more infirm and more vulnerable she got worse. I understood why, but it didn't help me cope with guilt being laid on me (in spades).
It didn't mean I didn't love her. I did, and still do. She was my mum, and a lot if the time things were good - especially when she had me to herself. But her demands ground me down.
Then I found I had friends with similar problems. So we formed AAARGH! Aged, Awkward, Argumentative Relatives Group Help! We had coffee or rang each other to unload confidentially. Similarly GN is a good place to download problems. Silverfish is not alone and I hope she feels GN is somewhere she can come to have a bit of a confidential moan.