How to speak up to an abusive relative without feeling anxious and stuttering
One of my relative is a very abusive person. I'm from another country, when I was 8, I was sent to USA to live with my relatives. My family is still in my home country. I lived with 3 of my relatives, but 2 doesn't really take care of me much. But the 3rd relatives (I don't want to use their name or something, so I'm calling them relatives) likes me. He buys things for me, knows what's good and bad, take me to places. He is really fun. But he has a problem, he gets mad VERY easy. At LITTLE things. Lets say he's buying me a new jean (true story), and he asked me how I like it. I said, "I think it's kind of small, I wouldn't be able to wear it for long, I grow fast". He would get REALLY mad, saying "I'm buying this for you, you haven't even say thank you and you're already complaining". He would curse at me, calling me names for usually the rest of the day. Something as small as that REALLY ruins my day. And if you think I'm not upset by it, I cry a lot of times. I miss my parents a lot. But being cursed at, yelled at, and sometimes hit at, makes me miss them more. He would also hit me, in the face. I'm not going there though.
3 years later, my family came to the USA. I was very happy, but secretly, I was happy I'm not going to be bullied around by him anymore. But no. He moved to another apartment recently, but every 3 weeks or so, he would take me to take a haircut because I don't like the haircut my parents get me. As soon as I get in the car, he would start questioning me. He would look at my hair and say why is it so messy. It's really not. He would start cursing about how he spent his time to get me a haircut and all, but it seems that I don't take care of it. To me, my hair is fine. It just got long, and the wind kind of blow it up. He would curse, calling me @ssh0le, and more.
So now, I really want to stay away from him. But he calls my about once a week asking me to go places with him. He doesn't have a job so he's got LOTS of time. I really don't want to go, so I start politely saying no, making some excuses because I really don't have enough courage to tell him the truth. After hearing it, he would get mad and start saying stuff like "You always inside, your face is getting fatter and fatter" and things like that.
I've been very polite and persistence to him. But he's gotten out of control. I want to speak up to him real bad, but every time he calls, I would have knots in my stomach and start talking very quiet and stuttering.
I really want to know how to stop feeling anxious and nervous and really speak up. I know it's emotional issues, but I can't take it anymore.
One of the reasons I'm afraid to speak up to him is that he's done quite a lot for me. He's abused me. But he's done a lot in the past. Not anymore, because he just gets me a haircut once every 3 weeks. That's why I have trouble speaking up to him, because I know if I do successfully gather my courage and speak up, it's going to be rude. I'm afraid he's going to bring up things like, I've done so much for you and you're not thankful for it or something like that.
PLEASE HELP
P.S. HE NOT ONLY CURSES AT ME AND MY SISTER, BUT MY PARENTS, HIS PARENTS, AND MOST OF OUR RELATIVES AS WELL (I THINK HE HAS BIPOLAR)