What can i do with this situation? urgent help?

So im 20 and dnt really get along with my mom. i try gettin close to her but she just pushes me away. i dnt understand what i did. right now she perfers and believes her man everything he says. she kicked me out bc her man didnt want me there and i had no where to go. thou there is this guy that lives next door to my mom and has been wantin to date me for like 5 years. i dnt like him! im mexican and got no papers and couldnt keep studyin. i want a carrer and a job. right now i am stayin with him and has told every body we are dating but we arent! if i do start datin him i can have everything and then get my mom her papers. will she change her mind and see me a different way? i dnt know what to do. this guy also has a gun and im scared! i have no where else to go. i was thinkin of leavin to mexico.