Marrying someone against one's wishes

My question is regarding my nikkah. When I was 16 years old my parents wanted me to get engaged. We agreed on my cousin and they gave their word. Since I live abroad I didn't have much contact with him. When I went to Pakistan, I lived with him and saw no compatibility. I told my mother that I didn't like him anymore. After a while I started talking with another boy with whom I was interested, we planned on getting married after I had finished my studies. Now last year before my nikkah took place we were supposed to leave for Pakistan, my mother asked me if I still liked my cousin on which I answered no, but I also didn't tell her about my relationship with the other boy. I said that I want to study and not get married so soon. We went to Pakistan and there they wanted to get my nikkah done. I had to tell them the truth that I can not marry my cousin because I like someone else. After much emotional blackmailing I agreed and told her ok, but soon I realised my mistake. My heart still didn't agree. I tried speaking to one of my aunts who assured me that this nikkah won't take place since there are only 2 days left and much preparation to do. I believed her and, I got satisfied and said nothing. Now, one day before going back home they brought the Imaam and planned the nikkah. At that time I begged and I asked my aunt to please stop it but she said it was too late if I don't agree now, my dad can divorce my mother and she can also get a heart attack. Being in that much pressure I signed the nikkah with the intention that I will later break it. This was one of my biggest mistakes but I was left with no choice. My question is, is my nikkah valid? Can my parents ask me to break it? I have no intention to stay with my present husband. My parents are asking for the validity of the nikkah.