I dont know what to do.....(need advise on my marriage)?

My husband and i got into a big fight cause of his addiction to pills and drinkin while taking them. i told him i dont want to see him die cause i know it is very dangrous and he also get really mean too when he's doing it. and he told me he wants a devorce cause i told him he needed to choose his family or drugs and to get help cause he is really bad addicted to them. He trys to use the excuse he has back problems and i do know he does but he want go to the doctor cause he dont have the money and at first i didnt mind him taking loratabs for his back pain but then he got started taking other pills that are light green with s/90/3 on them and he tryed to say they was for pain but i looked it up and it said it was used for mentle and depreshion. and he's got bad where he's lieing about paying bills and buying the pills. And on top of this he's been treating me like crap and calling me names and running off and he'll tell me he wants my son and i to leave and he wants a devorce and when i go to leave a pack he startes begging me not to go and he's sorry. we have been marrid going on 4 years in 2 months and i beleive in the for better and for worse but i feel like i'm nothing to him and i dont thing he loves me anymore cause all his love has went to pills and drinking. My life is tored up so bad my heart is telling me not to leave cause he needs my help to get off but when i ask him to choose he choose the drugs over my son and i and i'm tiered of getting hurt and being felt like i'm nothing but bead to him. What should i do?? I need some real advise. please dont come on and say mean things. i want to know if i should leave and give up even though i dont want to or how can i get him help??