AIO my grandpas new girlfriend is being disrespectful to my family and I’m about to go off

So my grandma passed away about 10 months ago, my grandpa has been really struggling with grieving over her, as well all are. It was a long battle with cancer, my grandpa started dating this lady 3 weeks ago and she lives near us… he lives outta state. He had been staying with my family, my mom is trying to recover from surgery and can’t really walk right now without an immense amount of pain. He came in to help my mom as we all have full time jobs I’ve been working from home the first couple weeks but I had to go back in so my grandpa tapped in. Well his girlfriend is coming over whenever he is there and she is ignoring my moms wishes by trying to move furniture “because it would look better this way” after being told to stop twice or change up her kitchen and telling her well it’s not like you can do anything about it… right now I’m out of state for work but I am fuming mad. After the phone call with my mom. If I was there I might’ve had words with an old lady. She is demanding of all of his time whenever he comes to stay with us now she is calling him as soon as he wakes up and is demanding to know where he is and he spends 14+ hours over at her house everyday. My dad had a talk with my grandpa and my grandpa said he would talk to her but honestly I don’t like her and I think he’s rebounding because he misses my grandma so much he’s just looking for anyone that brings him that kinda happiness. She goes to my Chruch and keeps trying to sit next to me and honestly I wish she would leave me alone… and TBH that they would break up. I’ve seen a side I don’t like and my grandpa is the sweetest man alive, he doesn’t need that in his life. Am I being too over protective and overreacting or is this a valid crash out.