Hi there - well if you want somebody to tell you you're not the crazy one, and that your partner sounds like a completely typical addict, engaging in completely typical addict behavior - consider yourself told. He's lying to you but more importantly he's also lying to himself - he's telling himself he can go back to just using cocaine for the fun of it, that he can "keep it under control" this time - those are standard addict rationalizations and outright nonsense, of course.
Addicts lie, that's what they do. Even the best of them are eventually dishonest in the extreme. Of COURSE he's going to try and make it look like your problem, that you're being "controlling" or "infantalizing him" or "being hysterical over nothing." The best defense is a good offense! If he can make you think it's your problem and not his, or get you worrying over whether you're doing the right thing, then that takes the spotlight off his behavior (where it belongs) and puts it onto you (where it doesn't).
In Al-Anon they suggest that you focus on yourself and the well-being of those in your care. If it were me, or at least this is where I've gotten to with my son, I would stop trying to control his use or catch him out lying or check up on him. I would also, quietly if you have to, stop putting much, if any, stock in what he says. Certainly don't make plans or orient your life based on anything he says being the truth.
Sometimes it helps, too, to take a good look at your situation and see how well-prepared you might be to go on if your partner isn't in the picture. I'm not saying to make any decisions or take any actions about him now, but at least think about where you stand in terms of employment, financial cushion, your support network, etc. It will make you feel as if you are taking back a bit of control of your own situation, KWIM?
Good luck to you!
Jane