Lying... Again...

My husband has been caught lying for the 1000th time last night. He has his Facebook in my daughters tablet because he was using it and my daughter and I came to my moms house as he gets out of school. We were watching a movie on the tablet and a FB messages scrolled across the screen saying "yeah I can get you the 20." My curiosity I look and he apparently is buying marihuana. So I asked him about it straight up. And his story kept changing. Then accused me of going through his stuff. Thats not even the issue obviously!  So I still do not believe him and this morning I go to see if he told them that he didn't want it anymore (like he told me he did) and all his passwords were changed. It bothered me. Because it just seems like he is lying to me. If he would be honest and just tell me "yeah I wanted some" different story rather than 6 other stories of for someone else and giving back to someone or selling it back. But I asked him why he changed it. He said he couldn't remember his password. (It was our wedding date).
I just feel so fed up with it. Petty lying and bull shit! I love him and am so thankful for him but freaking Seriously!  Does our marriage mean nothing to him!!! I'm so broken hearted over all of his lies and I'm afraid that I'm going to end up hating him and resenting him.