His mood swings scare me?

My partner has mild Aspergers and isn't great when it comes to dealing with certain emotions. When something makes him cross, he can't manage his anger brilliantly and often shouts at everyone near him and swears, and sometimes punches walls or throws things. For example, today he went into town with me to do some shopping before work, and left early so he could get himself ready. We share a house with his parents, who had locked the door before they left (they usually leave it open as we live in a very safe, small village) and could not get in to get changed. When I finally got back and let him in 5 mins before he had to be at work (it takes him 5-10 mins to walk there) he blamed both his parents and me, shouted and swore and stomped about upstairs. It scares me how he gets because when I was a kid my dad was violent, and when he shouted or swore it often meant me or my brother getting hit - I'm quite sensitive to shouting and things like that now. My boyfriend doesn't know about my dad's violence though as I haven't been confident enough to tell him. How do I get him to try to manage his moods? I know he'd never hurt me as he's always coming to find me and is really apologetic when he knows he's taken it too far as I walk away when he starts to get really bad - I think its to do with his Aspergers and not being able to manage his feelings well. There aren't any support groups nearby for him or anything like that.