{{{{pregnant and giving the bf an ultimatum am i wrong?

My bf has been smoking weed since he was a teen and dosnt see the big deal with him smokin, keepin mind he is now 20 and leaves every night around 12;30 to go smke and some times he comes back at like 2 2;30. When i found out that i was pregnan the told me that he was going to slowdown but that turned out tobe a crock of ish he ha ssped up.. I cant stand it im about to be 5 mnths pregnant and i gave him the choice either stop smoking or he needs tol eave because im not dealing with that crap anymore.Then this dirt bag has the nerve to tell me that IM being SELFISH. While im 21 and giving up ummmmm just about everything to carry our first child. So he tells me that im just jealous that he can party and i cant and that he isnt going to stop. Am i wrong for feeling like he is putting weed before his child and I! Am I wrong for giving him the choice! What would you do in my situation!