How to deal with someone treating you like crap when you treat them nicely?

I ALWAYS help my dad on the computer, clean the house, get his stuff for him, etc. But when I make one little mistake or forget something, he becomes a monster. For example, he said I don't have any brains because I accidentally touched my baby brother's face with a strand of my hair. If he calls me and I don't come to him right away, he flips out. Usually he waits like thirty seconds, but I was applying a band aid to my finger and I said "Please wait." to him, and he freaked out. He only treats me nicely when he need something done to benefit HIM. He borrowed $300 from me, and still has not given them back. It's been over a month. Should I ignore him? Should I keep listening to him like I'm his slave? I don't want to talk to him about it because it goes in one ear and out the other, and when I try to tell him something he doesn't care, he's "too busy" on the computer. Please tell me what to do. Thanks!