Would my wife be part owner of the business and its assets and is it 50/50?

It is not clear what you are asking. Ownership itself would depend on how the business was set up, but if you are concerned with a divorce or separation then it would likely be a marital asset regardless that you may be the sole owner. Compare, perhaps, if you were solely on title to the family's vehicles, you would be the owner, but they would be considered and allocated in a divorce or separation.