when you give everything you have

What are you suppose to do when you be nice to a person like everyday bring them lunch and then they go behind you back and tell people that your annoying. It just makes me feel so mad and to know that they do that... i just dont understand i mean why cant they just be nice and at least say something to me and not go around telling everyone els and then having me find out from them. It just hurts you know to know that they do i mean i would just stop bringing them lunch but im a nice person. Maybe i should just stop talking.....i dont know anymore