Can anyone understand?

I’ve been around a lot people in my life the abuse weed, alcohol and drugs. All high school all my exes and best friends would do it and I wouldn’t care, I would be with them the entire time, but it never affected me until my present boyfriend. he wants to start smoking weed again after stopping the first month of being with each other and it gives me extreme anxiety and makes me very emotional to point I think he’s lying when he tells me he’ll only smoke once a week or month. I can’t explain my feelings towards it but I know I don’t want him to do it but I know I can’t force him to stop. Anyone help me ?

Btw I’m 23 he’s 27