You have a right to be free.
The freedom of conscience is guaranteed by the UN's Universal Declaration of Human Rights, Article 18.
Whether you wish to convert to Christianity or some other religion, or have no religion at all, you have a right to live in peace, free from fear.
If you are in the U.S. and are being harassed or threatened for leaving Islam, you have recourse. Contact the local police. Contact us at email@example.com and firstname.lastname@example.org if they don't understand or dismiss your plight. We will call public attention to your case, which will make it more difficult for you to be harmed.
And here are some resources:
This is a comprehensive site showing the human origins of the Qur'an, the truth about Muhammad, giving you answers to arguments in favor of Islam, and much more. Note: it is a Christian site, written from a Christian perspective. But anyone interested in Islam, and in leaving Islam, will find it a valuable resource.
Leaving Islam: Apostates Speak Out by Ibn Warraq
This book contains the stories of Muslims from all walks of life -- Muslims like you who have made the difficult decision to be free.
The Truth About Muhammad by Robert Spencer
The eye-opening truth about Islam's founder, from Islam's core texts.
Women's shelters in the Miami area (site of the first SIOA Religious Freedom Campaign):
Women of Power Restoration Program - elpoderdelaoracion.org
12100 SW 218 STREET, Cutler Bay - (786) 226-7883
Miami Women's & Children Shelter - miamirescuemission.com
2250 Northwest 1st Avenue, Miami - (305) 571-2250
Women's Shelter of Hope
Miami - (305) 886-5001