My dad just told me that once i turn 18 im not welcome anymore?

My birthday is in the middle of the school year and i plan to go to university. He said that he is counting down the days until i turn 18 (im 15 now). My sister is 21 and still lives at home and doesnt pay rent or anything. I havnt even done anything wrong, I was having a small disagreement with my mum about nothing and he just jumped in and told me that after i turn 18 I'm not welcome and that I had better find a new address. I dont know what im going to do, i know its 3 years away but he sounded really serious and was like yelling at me and it couldnt have been a heat of the moment thing because i was talking to my mum not him. My mum doesn't do anything, he is always yelling and screaming at me about things that arnt even important. I don't know what i can do. I do all these things around the house and no one thanks me, before i slipped over i put all the rubbish out and did the watching and cleaned out my rabbits cage without being asked. I dont know what to do, im so worried about becoming homeless