How do I deal with brother's initial denial and then taking over control?

I live an hour away and see mom regularly and therefore saw the issues with her memory way before my brother did and kept him apprised of the issues as they arose. He was in denial and kept saying it didn't seem bad to him. After two years of trying to get my brother to talk to me about mom's declining memory, asking to have a conversation about making arrangements, he finally spent a few days with her and could see it, and within a week's time had her moved into a locked nursing facility without my knowledge. He did all of this during the week when I was working and by the time the weekend came when I could get up to see her, it was already done. He refused to tell me anything despite me asking directly what was going on. I talked to my mom, but she didn't know or would be confused.

Now, I understand that she needs someone around to help her remember to take medications and supplements and the farm house she was living in wasn't a healthy environment, but I don't agree with putting her in a home. I think there are options that were not considered and am concerned now that he will continue to make arrangements and choices on her behalf without consulting me. His wife has power of attorney.

Any advice would be greatly appreciated. I have been asking for help and support in figuring out what to do because I am a single mother and work a lot to just barely make ends meet, but now I feel like rather than support from him, I have to fight against him to make sure mom's wants and needs are taken into consideration.