LookyBooky, thanks for your gracious post, I wasn't expecting that, mine crossed with yours.
Your comment about your mum hiding your DB's gift resonated with me because my mum lies to me (and herself) about the way she's treated by my brothers and 'dresses it up' in her head that all's well. But she can't truly lie to herself and that's where her depression spirals. It's very wearing.
I wonder if you, being the daughter (and therefore expected to be dutiful) has made your mum feel a sense of entitlement that is completely unjustified? I mean by that that she expects you to want her to live with you, expects unrealistic, unfair (compared with your brother) and entirely disproportionate levels of gratitude for her 'gift' to you? She may have meant it with good intentions but ultimately it was selfish as it came with a host of strings - painful ones at that.
I also wondered if you were the 'constant' in your mum's life? Being the one to do things for her, take her here and there - and carry the emotional burdens of trying to keep her mentally afloat? Your brother does none of that by the sounds of it.
I keep going back to read your comments and I spot different things each time. Your thread has taught me some things that I need to pay heed of, as uncomfortable as that is to realise.
Thank you again for your post, it was kinder than I deserve.