Fathers on drugs...

I’m 18 weeks tomorrow and over the weekend my boyfriend and father to my daughter on the way went with his friend for a guys weekend. When he came back he was acting completely out of character I brushed a lot of it off because he has a very eccentric personality. He admitted to me yesterday that he has been off an on dope since October. I’ve never been around it and I have no idea what it looks like or how it’s used but he admitted to using it around me regularly, I feel so stupid for not noticing anything. My doctor hasn’t done any type of drug test and I feel like I should request it but at the same time I’m terrified that I’m going to end up getting in legal trouble if it is in my system. Again I have no idea if that is possible. Just really trying to seek advice on how I should go about this. He has refused to seek treatment stating he doesn’t have a problem but I know me and my daughter are not safe in that environment and I don’t want him around her once she arrives.