What can i do when my partner is outa control on pills and drink?

i have been with my boyfriend for 6 years he has a majour drink proplem and used to be on crack cocaine valiums and heroin when he was younger which he stoped years before i met him, he also used to take seditives .every year for the last 5 years he has done a detox to stop drinking he always relapes shortly after in which he gets very drunk and becomes outa control then he starts to take librium and codiene that he had for his detox and tooth ache which sends him mad he shouts,screams, dosn't no what time it is he sleepwalks,smashes things and treats me terrible he has fits in which i have to help him i get scared .hes out of control completey i stay up all night to check hes still breathing he dosent eat or can hardley walk i care for him 24/7. he is only 27 and i am 22 he hates what hes become when hes sober or just normal he is the love of my life but and the man of my dreams but im tierd and down im tierd of it all the getting my hopes up to being let down then having to help him wile he relapes and goes totally mental his mum and dad have moved away which i no affects him i cant take this anymore i need someone to talk to i fil like im going mad !!!!!!!