What do I do about having charges against me for ault and battery?

Ok so it all started a year and a half ago, I started dating this guys ex-girlfriend and he didnt like that so he decided to start talking a lot of sh*t to me and my girlfriend then decided he wanted to try and fight me but I refused to fight that time because I was joining the United States Air Force and I didn't want to do anything that would jeopardize my chances of being accepted into the military. About a year later this guys happens to be at a little party my roommates were having and he knew my girlfriend and I would be there, he showed up anyway. So I decided to talk it over with him so we could squash whatever problems he had with me a year prior to that, one thing lead to another while we were outside talking and he lifted up his arm with a closed fist and I swung out of self-defense because I felt threatened and i hit him one time in the jaw and then when he was on the ground i put him in a sort of half-nelson so that i had control over him then that was it. The next day i found out through my roommate that i broke his jaw in 2 places and knocked out 2 teeth. Then I left for Basic training for the Air Force. While i was back home on Christmas break the dude put a warrant out for my arrest and i got put in jail for a day with a $40,000 bail. I have court on February 3rd and I'm getting charged with Felony ault and battery and Felony ault with a deadly weapon with intent to cause bodily harm. I have never dealt with anything like this before, I have no priors, I'm only 18 and the dude is 19 (not if that matters at all). If someone has any advice for me anything will help. Thank you.