my bf wants to buy a house but with...

My bf just told me that his parents own land in a different country & that they are selling it to use the money for another house here & he gave them the idea of well why dont you guys use that money & we purchase a home together & his mom said yes that's what I want. & so now he's telling me that he wants my opinion & my opinion is NO! & he said he will buy a house that has a grandma house where they will be staying but what he doesn't understand is that his mom will want to be over to see our 3yr old. & if shes not over our 3yr old will want to be only at her grandmas & sleep there & I dont want that. Now tr he reason behind my decision is because the main problem is my bfs mom & sister. They both made my life difficult when I moved into their home for 4 months. For example I decided to straighten my hair ONE night out of the 4mths & his sister came into the restroom & said uhh I just cleaned it can you pick up all your hair your shedding because you shed more than my dog. Okay now his mom only calls my bf to ask about our 3yr old & nothing else or when she needs money. She has said some nasty things to him & my bf still gives her what she wants. I dont blame him for loving his mom but I just dislike the fact that she tells him he needs to give his sister money for clothes & school supplies or movie tickets when all she does is talk crap. He says he is grateful to have them as baby sitters & that is why they deserve things. I'm just pretty stressed out about this because I dont want them in our property at all! I'm very sweet& have never said anything to them to not like me. My bf told me that I have the last day but I feel like shit saying no. please help!!!

Sorry I'm going to add some details left out....

His mom never helped us with anything we have been in our own apartment for over a yr & has only been here once & she lives down the street. She tells him his daughter will lose love for him by next yr because he works so much & she loves her grandma more than dad. Also told him that he needs to spend less time with me & more with her because I dont matter. The house will have a "grandma house" where she will stay which is not inside ours but can you imagine her not over because our 3yr old will be there. 🙄🙄🙄🙄

Oh & yes his sister says "nigger" "nigga" & laughs when she repeats her 😢