Tricky situation. I think the people who tell you that you'll regret not talking to him are correct.
A little similar to my situation, except that my dad was a good dad for the most part. Unfortunately he was also an alcoholic. So in the end, when I was about 14/15 me, my brother and sister went to live with my mum permanently (parents divorced when I was 8). About 3 years ago I'd had enough of his constant drinking and threats to kill himself and always crying which of course made me depressed. So I stopped talking to him. Last November he died. You'll never know how much sorrow and regret (and after this I really try never to regret anything, even bad decisions) I feel about how I wasn't talking to him when he died.
So in conclusion, be the bigger man and make an effort. Explain to him rationally, send an e-mail if you like, about why you weren't happy about telling him about your university rejection, and requesting that he stops attacking your mum about things that are nothing to do with her.
Really, do try to make an effort to build some sort of relationship with your dad.