The drug speed and pills?

My love has a problem with pills and speed. He was clean for almost 8 months and now he says he cant stop.. that he is addicted. We have been fighting a lot this last month beause of it. He tells me that the drugs make him not have feelings or emotions. I finally told him I couldnt do it and he told me in reply "Why does it have to be like this? I lvoe you so much and am stuck in the things im doign right now I just feel like if u really loved me youre going to be here for me" im return I told him that if he really loved us ((me and the 4 kids, 2 are his and the other 2 they call him dad)) the he wouldnt do what he is doing. He ignored me and we got in a fight((pretty bad)) and he left. Was gona all day and night... I told his bro if he talked to him to havehim come get his stuff... I packed it and put it outside, he came and got it last night. I hav not talked to him since. I dont know what to do. I want to let him go, but then again if you love someone how can I watch him just go ruin everything. All of his friends are loser druggies... along with his family. Im just so lost and confused right now.