There seems to be a correlation between opiate addicts and ketamine addicts, probably due to the 'escapist' properties of both drugs. While ketamine might seem like a better idea at first, really you are just trading the same addiction out with another substance. I think you need to really ask yourself what it is you are trying to run from. Your drug use and overall addictive tendencies are a product of a deeper emotional problem or possible a lack of spiritual practice.
For example, The part of your mind that may be weak is the area that deals with comfort, survival, and security. A problem can occur here for various reasons including a poor early childhood, or perhaps a childhood that was 'too comfortable'. Either way, it can create a negative reinforcement when it comes to feeling comfortable and secure in this world, and that could be why you turn to escapist drugs.
Have you ever considered going to self help groups or rehab? The actual quitting of the ketamine is going to have to be a decision, and then you have to examine ways to feel good without it. It's really not an easy process, but i can suggest something that really helped me, as i too was addicted to heroin and often used IV Ketamine when i couldn't find any, just to get out of the body i was in.
"The book, which examines many aspects of social mind control and mental imprinting, provides mind exercises at the end of every chapter, with the goal of giving the reader more control over how one's mind works. The book, which has found many readers among followers of alternative culture, also discusses the effect of certain psychoactive substances and how these affect the brain, tantric breathing techniques, and other methods and holistic approaches to expanding consciousness."
The book is called Prometheus Rising, and you can probably download it for free. Look, in this world, we often need ways to feel like we can mathematically calculate solutions, that is westernized thinking. This book offers a very understandable approach to getting to know your own tendencies better. I strongly suggest it, because as someone who responded negatively to the 12 step approach, i can say this book amongst other texts helped me more than any person ever could. You have to help yourself, and this is one way to do it.
I sincerely wish you the best, and honestly hope you at least give it a try.