Oh yeah, cutting can be an addiction. It can also be habit forming and thus addictive.

Your wife does have a reason to be worried because cutting can escalate to the point where it becomes life-threatening, as well an accidental cut can be life threatening as well.

Generally, once it becomes an addiction that you cannot seem to quit of your own free will - it doesn't go away, and it rarely gets "better" or easier to manage...

Have you sought treatment for it?