Please help with parents?

I know this might be kind of crap to some of you but im really worried. My parents worship my younger brother and i always get shoved in the mud. I always contain my anger but at times the lid just snapps and i have to have a go at someone for something. The other day for example, my parents were out and we were told to get ready for bed. My brother fell asleep on the sofa and i got him up and told him we had to go to bed. He got up and went into his bedroom and fell on his bed. I asked him if he had brushed his teeth and he didnt answer after a while i got him up and chased him around the house trying to get an answer out of him. At one point i sat on him and then i stood up. I was so mad and angry and i just burst. i told him how he was a spoilt brat and that he had everything compared to me. I told him about all of his possession that were worth more than my one possession (My laptop) I got so mad and i screamed for over half an hour at him. And today, it might seem stupid but my mum needed someone to go down to the shop with her and i had no pants so i told her to wait untill i had some and she got mad and i ended up going down in a summer dress that always fell down. I went to the shop and people were sneering at me but she didnt care (Or at least she acted like she didnt care) and on the way home we had four bags. One with milk and hair stuff, another with the washing powder, another with the bread and another with the fruit. She gave me the milk and washing powder and took the other two (The lightest two) I told her to wait while i pulled up my dress and she continued i ran with two heavy bags. She said we will stop half way. I stopped and pulled up my dress again and she continued. I called after her then gave up and ran to catch up with her. I told her we were ment to stop. She said that we would stop in the elavator. So i got mad and my hands were killing me by now. I threw the bags on the table and went to my room. My dad came in later to tell me to go and say sorry to her because she was in tears. I knew that they were crocodile tears and said no, she should be apologizing to me. Why couldnt my brother go instead of me? My chest was visible half the time i went with her but like her, he didnt care. i sat down and now i have to say sorry to her. Any ideas on what to do? I dont want to say sorry because i dont think it was my fault.