What should I do regarding those who revile Allah and His Messenger (peace be upon him) in my community, and am I responsible before Allah for their actions?

Abusing Allah and His Messenger is among the greatest of prohibitions and an act of disbelief (kufr). Your persistence in advising them and enjoining them from evil is among the greatest deeds, and it is the ritual of enjoining good and forbidding evil. It is an excuse before Allah and a way to dispel despair. If your staying among them poses a danger to your religion and the religion of your family, then leaving them is better for you and safer for your religion. If you are unable to do so, do not burden yourself. Furthermore, the balance between staying and leaving is up to you and what you deem most appropriate for your religion. It must be noted that abbreviating "peace be upon the Prophet" is inappropriate.