What is the usual amount of time that can be put on somebody to serve in jail for domestic assault?

Ok, my boyfriend and I had a big argument 2 months ago and I called the police on him for punching me in the arm. It left a bruise. The police asked me if I wanted to press charges and I said yes mostly out of anger. However that day I did not have transportation to go file the warrant so the officer went and done it. He finally got caught but on a DUI charge and the domestic assault charge also. He is facing a lot. I do not want to testify against him in court but I have a subpoena that I must go to court. I still love him and this is the first time he has done this in our 4 years together and he is a good daddy to our 4 month old daughter, he has always been there for her. He has court September 10, 2012 for this and I was wondering if the judge decides to make him serve time what is the usual amount of time that is served for something like this? What will probably happen? Can they drop the charges?, because that's what I want but its not up to me.