My brother took over caring for mom, and now he’s not speaking to me. How do I handle this?

My mom moved in with me after my dad died, it was a month ago. Since then she’s fallen a couple of times with injuries amongst other things she has trouble walking and standing and getting to the bathroom on time. I tried, I just cannot care for her, it’s very overwhelming, she definitely needs 24/7 care. I don’t know how my dad did it. I said to my brother we are putting her in AL. He said “no you're not” So now she’s living over there with him and his girlfriend. The gf is the primary caregiver and from what I understand she’s not happy. My brother is not speaking to me now that mom is there. He’s so angry, nobody asked him, he decided to care for her. His exact words were “I’ll be the assisted living” He won’t put her in AL because of the inheritance, I know that’s the reason. He’s not telling me what his plans are or how mom is. I find out by talking to my mom what’s going on. He’s always second guessed everything I suggest for mom, her house, or her finances, he says he will do it, but never follows through the best way and if he does anything it’s always a big fight. We both have POA. I just don’t know what to do, how do I handle him? I’m going crazy from the stress.