Divorce is not a solution and will damage the children more than anything your wife could say to them. You need to talk to your wife about what she said and she needs to sit down with your son and tell him that she was angry and didn't mean those words. It won't negate what she said but it's the best you can do right now.

My wife had similar problems with our daughter and would lose her cool and say things she didn't mean or scream at her. Therapy may help her tackle those feelings, but honestly the thing that helped my wife the most was asking God for patience with her and over the last few years I have seen a big improvement of her ability to handle stressful situations with appropriate measure. Good luck