dont know what to do!?

ill try and keep this as short as possible if i can . .

basically me and the other half have been going out 3 years in august im 18 going on 19, hes 21 going on 22 and were engaged, and we have a 2 bedroomed flat together my name is not on the tenancy cause i was 16 when i moved in.

ive been through quite abit at the moment with my mum being in a abusive relationship with an alcholic are relationship is extremely difficult at the moment.

anyway me and the boyfriend in a few weeks time surpose to be moving into a new flat together, we was quite excited, and choose what colour paint and things like that and basically planned the flat out,

well this horrible lad whos moved in just across from us hes a very nasty peice of work, drinks and does drugs . .

and my boyfriends brother sometimes pops round and my boyfriends nan wanted him to go round there and keep an eye on his brother, well now my boyfriend is now round there constantly getting sucked into it!

we have always had a great relationship and im his carer cause he has heart and hearing problems, well now hes started drinking to the point where hes getting drunk, me and his family are getting pushed out and in a space of 2 weeks hes changed dramaticly doesnt even stay in with me anymore, doesnt even come home, sleeps round this lads flat, i rarely see him now probably about 5 minuites a day and thats when hes just looking in the cuboard and getting food!

he doesnt want to know his family anymore, he keeps saying he wants me out his flat

he came back a few minuites ago, and said im getting my sleeping bag and sleeping round his again tonight, we started to have abit of a row and he said i want you gone by saturday!

his family and his other friends think hes being so sefish, and his dad is surpose to be coming down tomorrow and talking to him as hes mad with him!

i just feel so upset and dont know what to do, cause im my boyfriends carer i dont have a job, so if i go, i have no roof over my head, no money, no job!

and i also have 4 cats, 2 birds and a hamster, and i just dont know how i would cope on my own.

i just wish my boyfriend would snap out of what hes in, but i just dont know ?