My husband smokes pot sometimes and it bothers me.?

Okay so please read all of this before just spouting off an answer. My husband and I both have great careers, good family..etc..The main issue is that all of his friends are a bad influence. He had smoked pot for 10+ years and when we got married he agreed to quit. He quit for 6 months and then one day had a relapse. This weekend we got into this "talk" about it because I had suspected it . Should I be mad about it and how he had lied. My Christian brain says why is he jeopardizing our walk with God and why is he so immature? On the other hand, can I honestly expect someone to quit smoking pot that smoked for 10+ years so quickly? He loves me and he is good to me. I am just so confused. I also think... is it really hurting me? I don't want to force him to do something because I think that will make it worse. I haven't been married that long so i don't know how to handle this without it getting bigger or causing me to dwell on it and make myself crazy.