Hi Bellagirl,
I have been in your shoes, and if I was you, I would leave and live your life. Sadly users underestimate the effects of what they are doing on the people close to them.
I am married, and have a child with a recovering cocaine addict. The ONLY reason I didnt leave was because of our child, and the hope that at some point he would change. He has, but for how long, I dont know.
I also have an 18 year old from a previous relationship, and if I was talking to her (I presume you are quite young) I would tell her to get the hell out of it.
Cocaine creates paranoia, and they become so detached from reality that they actually believe they are right and everyone else is wrong. The reality is that because he’s probably lying to you about his ‘problem’ that you must be lying to him too.
Take care, and I’m here if you want to talk x