Stay strong
My attorney brother's reason for not selling the house is that I won't give keys to my non-attorney brother
I have been puzzling over this. Did brother A (attorney brother) say "I can't sell the house because you won't give brother B (non attorney brother) the keys"? There
is a logic here. The house would need to be cleared before it could be sold and generally it is easier to market a house if it has been emptied and cleaned since the previous occupants effects are likely to be offputting to buyers, unless they want to buy to let and plan to keep the furniture.
B has already done a recce of what's in the house. As you have indicated, this is none of his business, but he and A are working together on this. Your original post stated that the house was empty, but it would appear that it is unoccupied, not empty, and your aunt's effects and the house itself are vulnerable to theft from outsiders as well as from relatives.
It would appear to be in your aunt's best interests to clear the house of possessions and put these into secure storage. If it's just a matter of low value furniture and household goods then you might be able to agree between you to sell these. Even low value household effects would sell for a few hundred pounds, so this money should be returned to her estate. Since you mentioned jewellery I wonder whether there may be other valuable items, in which case anyone wanting to take these should pay for them following independent valuation, and add the funds to her estate. I don't think you can trust your brothers to do this.
As attorney you should certainly insist that B provides an inventory and valuation of the jewellery and proof that he has insured these and has them in a secure place, e.g. bank deposit box. Perhaps if he realises that he has taken over responsibility for insuring the jewellery he might return it to you!
Hang on to those keys and seek legal advice. We're all rooting for you. I know you can do without this distraction when you want to concentrate on your aunt. Equally if you let A and B push you out you will always feel you let her down, so you must stand firm. It really isn't about you getting your share, it's about doing the right thing. Get as much help and support, legal and emotional, as you can. It is hard to stay strong, but it's amazing how much strength you can get from being supported on TP. It keeps me motivated. I hope it does the same for you. Katrine xx