Too Much.....

I think being too nice has also disadvantages. I guess the saying "too much of something is bad", rings true. There's nothing wrong with being nice,i think it starts to get bad when other people takes advantage of you being too nice. What am i saying? It's about this male tenant we have. We treat him like he's one of our family, it's just that he starts to get too comfy with us. He eats here with us, borrowing the things we have even my lappy, overnight(he could borrow it for 1 or 2 hours but overnight?), he just barge in inside our rooms as if its his house. If there's one thing i really hate,its when somebody doesn't respect my privacy and when somebody doesn't know how to respect a closed door(unfortunately our door lock doesn't work,but can he just knock). My mother grows a certain fondness for him,treating him like a son,he on the other hand took advantage of it,and i hate it. There should be some certain gap. Am i just jealous or its just that i just don't like what i started to see?  he started to ask favors,barging in our rooms without knocking and comfortably lie there as if its his,enjoying all our home equipments,eating here.seriously?...i mean seriously. And when i observe something i don't like at all, i immediately keep my distance. I tell my mom about it,and she said that I'm just misinterpreting things wrongly,are you for real mom?...I'm not blind,he's taking advantage of us being too nice. I'm not the type of person who has a certain ability to go tell people to fuck off when I've had enough, i'll show him that i don't like what he does, through my actions, i'll not be that friendly anymore,be cold and keep my distance,i hope he's smart enough to see that i don't like him.