fell in love with a Addict

Me and my guy friend started being together off and on for the past two years. we would always party together n drink until he got locked up for something non drug related in November 2013 He started writing me all the time and in Jan 2014 we decided to become a "couple" and talked everyday fell more and more in love ..he got of jail early March 2014 and a few days after he got out he relapse and promised to try his hardest to not start doing drugs again..we both wanted to be together without being high or drunk all the time, but somthing happen and he suddenly lost someone he was very close to His father past away very sudden from a" over dose" ..and he took this very very hard..and he would start sneaking off at night to get high n I would get mad but after him doing this a few times I didn't want to be without him so I ended up leaving n getting high with him..well that started four months ago and Now he has changed into a deferent person n not only doing one drug HE has now went from weed to meth to taking so meny pills I'm scared he won't wake up sometimes, and I've even herd that he is now doing H off n on...he confessed to me that yes he needs help and is going to go to a inpatient rehab but he has to wait for spot to open..and in the mean time he keeps staying out all night n coming home all high and acting out of it and I don't Know how much of this I can take but if I leave him n something happens to him I'll live forever with guilt...??so my question is what should I do. ..should I walk away and give up on someone who I love so much.even tho if HE was sober he wouldn't be doing the things he is doing now ..or should I hold on to him and continue to let him treat me the way he is? ???