I can't believe it I'm back at square 1. I

I can't believe it I'm back at square 1. I stopped smoking meth for over 8 months for alot of reason the biggest was health issues and wanting to be able to have a child with my husband. I have been more willing to stop then he has. One of the biggest reason he stopped I believe is because I said I would leave him for good. After all this time he decided to go get it again...I asked him not to but he said he is not able to focus on his music like he needs. I know it's sounds stupid but he always says that I don't support him and what he likes which is music. So I didn't argue about it. Maybe I actually wanted it too :woman_facepalming:t3:
I thought I was strong enough but as soon as he lit it I had to smoke!!! Once it was done 2days later he went back again...what should I do we are always around each other and work together so it's hard to leave