My wife is an alcoholic and regularly drives with our 9- and 10-year-old kids in the car after drinking.
I am not licensed to practice in your state. Therefore, I cannot inform you as to the specific laws of your state and can only provide you with general information concerning child custody.
Generally 9- and 10-year-olds are considered too young to testify in court in a divorce case. Instead, you should consider a child custody evaluation.
A child custody evaluation is a third party, usually a doctor/therapist who is at minimum a Licensed Clinical Social Worker (LCSW). The third party conducts interviews with both parents and the children and then renders an opinion concerning the custody of the children.
The court can then consider that opinion when deciding child custody if you and your wife are still unable to agree.
Other things that may help you are: criminal records of your wife being charged with alcohol-related crimes or other evidence of the alcoholism (pictures/videos). You may be able to discover additional helpful information during the evidence gathering phase of your case.
Remember, I am unable to provide you with anything more than general child custody tips, so please consult a domestic litigation attorney in your area to obtain specific advice as to the laws in your state and how they impact your circumstances.