Nikaah of the girl without her permission

I have a question about the validity of Nikah. I loved a guy and my sister and dad found out about it, without allowing me to tell them anything and express my feelings they got me engaged to my cousin without my permission but I don't really understand what sort of nikah it was because they never asked me but I still love the person I am involved with and I want to get married to him because I know he is the right guy for me. If I get married without the consent of my parents, will my nikah with that person be valid? Please I need the answer as soon as possible, and also if I want to run away from the house and come back afterwards when everything gets back to normal, just need to know if my nikaah will be valid and accepted in Islam?