My DP wanted to buy some 'herbs' last night and asked my permission because he knows I don't like him using it and I've told him he can never use our money to purchase it. We are lucky to have a little money this month and he wanted to spend some of it on this stuff. He asked, I said no. Then he stayed there and I could see his cogs whirring, thinking of ways to change my mind. My answer stayed the same the whole way through his attempt to 'reason with' me. In the end I said 'you're going to buy it anyway aren't you? Even though I said no?' I wanted to know what my opinion was worth if he would ignore an answer that he didn't like.
He didn't buy it in the end, or so he says. We already have trust issues so it's tricky to work out if he's telling the truth sometimes. I told him to never ask my permission on something again unless he's willing to accept my answer. However, not asking permission means he will suffer my wrath if I find out he's done something I wouldn't ordinarily let him do. I sound controlling, but it's with good reason as he cannot handle money responsibly and we have a toddler to think about.
How should I realistically deal with this, though?