Relationship, drugs, help:?

So I've been seeing this guy for about two months now and things are getting serious. We spend almost every day/ night together we talk everyday we both made sure we're on on the same page about what we want and things were going great. Until the other night. At the very beginning when we were just friends, wehadnt done anything, I brought up the subject of drugs letting him know that if he ever chose to do any hard drugs that I didn't want to be around him. He completely understood and said he cared about me to much to lose me over that. (He admitted that he had tried drugs in the past) anyway his friends were all planing a night out which I was invited to. But as the iPad is connected to his phone so I could see all the messages which they all started saying they're getting some pills and speed. And to my surprise he agreed and said hell try and find some. Then one of the messages was 'that was close ally(me) was playing on the laptop' 'And?' 'She hates drugs, but zero fucks given by this guy!'
Fwi I didn't see the messaged at the time they were being sent I saw them when he was asleep on the couch. So I went to sleep and in the morning packed my stuff and left. I didn't say anything and he won't know until he gets home. So what should I do now. I really really like this guy he's been amazing to me in evert other way but I will not be in another relationship with a guy on drugs. I've been through it once and it was horrible. Please any advice is greatly papappreciated

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