my husband is using meth behind my back

I've caught my husband for the 4th time with meth. I haven't caught him in the act but what I've found is enough and he has admitted it to me. First time I caught him was in his text messages. He asked his friend if he had some "coffee". His friend answered him by sending him a picture of a big bag of meth. I called him out on it and he told me he was getting it for his deckhands...and one of his deckhands at the time was my brother. I blew up on him BC my brother is an addict and he has watched my family go through hell dealing with his addiction. I kind of knew he was lying about it and had a feeling that he was buying it for himself also. The next time I was cleaning out his work bag to wash his clothes and found a pipe that's used to smoke meth...I smashed it and blew up on him again. First of all it was in his bag which was in arms reach of our 2 small children. He admitted to using but told me he hasn't used in months. (which he lied about again BC I read his text he and he had used à week before that mothers day weekend). He told me he was sorry and promised he wouldn't use again BC he didnt want to lose his family he asked me to please trust him. I was also 31 weeks pregnant at the time and the stress put me into early labor 3 days later...thank god they were able to stop it and I was sent home on bed rest. I just recently caught him again in his text (I know I'm wrong for that but I have my trust issues w him). I went bring our oldest daughter to dance class. He stayed with our 5 year old and 2 month old. That night I went through his text and seen that he told a friend that I was gone and he can come bring his dope whenever. I havent said anything to him about it yet..but I'm pissed. He had our 2 kids here w him while he made that deal. I'm thinking about leaving him. He obviously doesn't care about losing his family that much. I also suspected he was on meth the week we took our new baby home. He's a good husband for the most part and a good father. But I can't deal with him using behind my back especially with him knowing what me and my family are going through with my brother being a drug addict and meth is one of the drugs that has taken over my brothers life. I dont want my kids around it and I don't want him to do something careless and stupid one day that will get ourkids taken away. I don't want the added stress. I need advice. He can tell me he'll quit as much as he wants but I'll never believe him BC he's done lied to me about it already. I think I may want a divorce. Is that what's best for me and my kids?