Im to my edge and I dont know what to do

So, I wanna start with some history...My wife and I have been together for 7 years, married for the last two and up until this last year we have never had any real true problems. Things have gone great, In Jan. we hit a dry spell things stopped happening in the bedroom, she stopped talking to me. I would try to talk to her and even try to start things up (getting turned down every night for a month straight really pushes on a man). Im a avid online gamer, I had quite a bit of friends online a few female, and with the lack of attention I was getting from my wife I began flirting with a certain one. We began talking more and more and things led to more sexual discussions, sharing of pictures, sexting. Then she started talking about wanting to do more. Things got more intense and my wife started noticing I wasnt trying anymore, she then started paying more attention and due to the fact that I have never tried to hide anything from her it was pretty easy for her to find our conversations. It hit her really hard and I didnt try to deny it. I came out, it took alot for her to stay with me...she felt as though I betrayed her. Well since that has happened I moved away from the gaming server I was on and started new, trying my best not to get to close to people because once again things have gotten dry and nonexistent. I tried talking to her and well, one night when I went to talk to her I caught her taking drugs. She tried to hide it but Im no fool and made her show me and we talked, She told me that she started taking these drugs at the beginning of the year about the same time things got dry for us the first time. I am trying to understand, hey we all wanna have fun. But lately these last couple of weeks she hasnt gone a day without something. Its mainly muscle relaxers and anxiety meds, and when she takes them its like she is drunk, she cant walk straight, she slurs her words. On her days off all she does is get high and sleep, she is in and out of this drunk high all day. When she gets home from work the first thing she does is take a few pills and then the rest of the night she is stumbling around laughing. Multiple times when she is that high and I try to get her to eat something she will literally pass out with food in her mouth, or a drink in her hand spilling it in our bed. Now I am explaining all this because I talk to her, I feel like I cant ask her to stop, I have no room to tell her to do anything, she has forgiven me for my betrayal and I cant help that its my fault she is doing this. When I talk to her I ask her if she can cut back on how much she takes, she nods and acts like she will and then that night she does the same thing. Every night since I have found out has been worse than the previous night, we cant do anything together anymore because she isnt functional. She cant get out of bed and the only times she does is when she has to work. Tonight I went to bed to surprise her (it was supposed to be my game night but I called it early to spend time with her) she was already so out of it that she was drooling on her tablet and in and out of sleep. I laid down and she woke up saying that she needed to finish her game and started spreading the drool all over the tablet not realizing what she was doing. I told her that let me clean it up for her and I grabbed it and she said that I treat her like a twelve year old and that I just need to fuck off and let her do what she wants. I feel like I have been very understanding these last couple of days, Im from a family of addicts and I try to keep myself from substances. Ive been down the road of addiction and pulled away, my wife has never really experienced anything like that, she was always a shutin and did whatever her parents told her, so I can somewhat understand wanting to get high alittle bit and enjoying oneself a bit. But I feel like things are getting bad and I don't know what to do. I feel like I should tell her she needs to stop, especially since when I ask her to cut back she has yet to do it..... But at the same time I really dont want to cause problems, I feel with what has happened at the beginning of this year will turn up a fight and she will blame this on me and I really cant take that I really needed to vent more than anything, I dont have anyone other than my wife to talk to and with things getting bad like this the other people in my life I wouldnt want them to know about it as they already think less of my wife anyways.