Your'e right. People do lie, and cheat, and stab you in the back. There will be people who use you, and don't love you even though they say they do. But you can't let that stop you from living. Because there are people out there who do love you, and would never hurt you. You have to find those people and keep them in your life forever.
Some people will do you wrong in life. People will say things about you that you never think they will, people will lie on you, people will cheat you, and people will purposely hurt you to try and make their selves feel better. There will be people in your life that you thought would be with you until the end, but they will fall out of your life. There will be people in your life that say they love you, until it is convenient for them not to love you anymore.