My mom (f48) is moving on too fast for me (f18)

Hello everyone, I’m 18 and I still live with my mom.
A month ago I started attenting a school which i always have to go to for two months straight. In this period of time i can only be at home during the weekends because of distance (its really reallu far away). This is necessary for the training for jobs where I live.
About two years ago we moved away from the rest of my close family because my mom and dad had a divorce. It was very very ugly. I basically lost everything i knew in the blink of an eye. My belongings got thrown in a truck and tossed in front of our new apartment. There were verbal and physical fights including me and it was just overall awful.
Since then i have become the happiest Ive ever been because i finally live a normal life in normal surroundings (that sounds dramatic but i am expiriencing a whole new version of living rn and it makes me feel like a flower finally able to bloom) . Anyways, all this has obviously made me extremely scared of losing everything i all over again like my home, my stuff and even my friends (since i cut contact with a lot of people i knew because of the divorce and the fights). Now my mom has a boyfriend and while I’m away from school she has been staying at his place and is also only at home on weekends. I knew beforehand that if this is gonna happen she will certainly not wanna live with me anymore because she is very much in love. It was always planned for them to eventually move together but i knew that if she starts to live at his place for so long she will definitely wanna move out asap. I thought that it will only happen in a few years since we both enjoyed living together but now i know that she does not even wanna be here anymore.
As of now i cannot afford a place of my own nor would she let me live alone. She thinks i cany handle it and maybe shes right because i get lonely.
Today she talked about buying furniture for her boyfriends house and said that our apartment is a weekend house and that hurt me so much because this is my home. Just because i cant stay during the weeks anymore for a limited amount of time, doesnt mean that my home is at school now. I love my room and it took me a long time to adjust i think. I am dreading thinking of giving it all up again so much. I really have abandonment issues and i dont know how to convince myself to move again.
So how do u think i should talk to her about this? She instantly gets offended when i say that her moving on so quickly is an issue for me. She called me selfish several times and she just doesnt understand that i dont not want her to leave because I’m evil but because i am terrified.

Any advice or thoughts would be great 🙂
I’m sorry if my grammar or english is bad, it isnt my native language.