How do I warn him?

Okay so on the weekend my friend is having a drink up at a hotel, my boyfriend who Ive only recently started dating is coming.

He’s against drugs and doesn’t like it and I completely understand. I would never take drugs either

But some of my friends and others who I don’t know are planning on taking drugs and I wanna warn him so he doesn’t get a shock but I’m so nervous to tell him.

My ex hated my friends. He had a problem with everyone and didn’t want me to hangout with anyone so now I don’t want my new boyfriend to have a bad impression on my friends.

How do I say it to him???