Found out partner does drugs

I knew he could be heavy drinker, but didn't know he took drugs. He told me that in the past he took drugs, but that he doesn't anymore. This was when we was first together.

I had no reason I guess to not believe him. There was a time few months ago, I had asked him if he had been on something else other than alcohol.

Last night he came home, I knew he was drinking because he was out with his managers. He had previously told me his managers do drugs. He said last night he couldn't carry it anymore and he needed to say it it's been on his chest. He's talked to his therapist about it but it's still heavy on him.

He knew that I hated when he smoked weed, which is probably why he didn't tell me. Even didn't like how much he drank, because once he starts he goes on benders for days. That's when he gets paid, then after that he won't drink for the rest of the month. 

I just don't know how to feel, I don't like drugs and wouldn't willingly date someone that I knew takes them. He says he only does it socially, and that he's not addicted I just feel like that must not be the truth.

What I realised is I've dated someone like my mum did, her ex drank constantly never stopping, & did coke. He got killed from being so drunk and falling into the tracks. Part of me saw my partner going the same way, it's been making me anxious for so long.

The worst thing about is that, he's doing it with his managers. They are always getting him to go out drinking with them, and apparently drugs. 

His job is been what's helping us survive, I've been unemployed still trying to find a job.