If this is your first relationship with someone with ADD/HD, in the beginning, and for several years there can be what is known as the “Hyperfocus” phase. I am a member of the site “The ADHD Affect on Marriage”. On this site, there are many stories from “Non” spouses who feel they got the old “bait and switch”, when they married their spouse. Several spouses report a change either after marriage, or following a major life changing event, such as the birth of a child.
You don’t deserve to be abused, and if you were to stay with him and he is refusing to change, it will not set a good example for your child. I am sorry you are going through this.