Worried about my brother taking advantage of my mother. Thoughts?

Recently I went to mail my Xmas cards and I asked my oldest brother for his new address. He wouldn’t give it to me and my mother told me over the summer that he was “renting” a new home. In the meantime my father passed away almost 3 years ago and he was asking us siblings about my mom building a family house in a high end ski resort in Colorado that’s not very easy to get to and is very expensive.
My mom mentioned to me that he was building a home there last spring. Keep in mind that he’s been unemployed since shortly before my father passed away, it’s been 3 years since he’s had a job. I got my brother's new address from my youngest brother who had to get it from our teenage nephew. It’s a very expensive house and found a 7 figure mortgage was taken out on 70% of the purchase price. Since my father passed away he went from never owning a home and now has 2, one in the state where he lives and is building a luxury home in a mountain ski town in Colorado. I always suspected my parents were helping him over the years and while signing off on some docs from my dad's estate I noticed that he had given my oldest brother over $200k cash within the year before he died.
Needless to say he’s the prized child of the family and I was surprised that my parents were giving him that type of support. They always hold him in high regard. My relationship with my mother isn’t great and he’s very close to her, they talk everyday. Looking back when my dad passed away he took everything, even stuff my mom said that she would give to me somehow ended up with him. My mom now lives in the same state as me, she moved into a family vacation condo that they’ve owned for over 20 years. Just after my mom died she invited my family to come and visit. A few days before the visit, she cancelled saying that it’s wasn’t a good idea for us to come because “things” haven’t been accounted for in my dad’s estate. Looking back my eldest brother wanted to get down there before me so he could go through my dad’s stuff.
Recently I visited for lunch and she didn’t invite us up to her condo. I get a feeling that my brother doesn’t want her around me. She’s secretive about her finances and when she talks about them she uses the word “we” decided as if my dad is still living. My brother has told me several times that he has no involvement with her finances, I never asked him. I’ve come to the conclusion that it’s her money and she can do whatever she wants with it. I don’t ask my mother for money and I’m grateful to be financially independent.
My mom is getting old and I would like to have a better relationship with her and my family. It seems she’s not interested and would rather be with my brothers family. My mother takes care of herself and doesn’t need daily care as of right now. I wish they weren’t so secretive about how she’s helping my siblings and it seems at times like he tells her what to say and not say. Thanks for reading!