I love my dad but I can't express it, please help?

When I was little, my dad was the best dad anyone could ever have. He did everything with me and we had the best relationship and I have never felt closer to anyone before. But things changed ever since I turned 12. He began to become very distant, we barely talked at all and he would get mad at me for no reason. I also hated the fact that he smoked and has been smoking for the past 25 years, and I am so afraid to lose him that I even have extreme nightmares of losing him and waking up crying hysterically. However, the main problem between us is we have no communication what so ever, one time we had a fight that lasted 3 months with him and I not speaking a single word to each other, and every time we have a fight, I have to be the one who always has to apologize even when he was wrong. Right now, we barely speak at home, and he's like a stranger to me, and even when we speak, it turns into a big fight with me screaming at him and him screaming at me and saying hurtful things like "I wish I didn't have a daughter like you, I don't even love you" etc. These things really hurt me, and I have confronted him before but he just never changes. I want to have the relationship we had before but right now it seems to me that is near impossible. I do admit, everytime we fight, we BOTH say hurtful things, and I always regret it afterwards, but I just can't help it. I've tried ignoring the comments he makes but there is a certain amount of pain a person can take. So please help me.. what should I do?