don't let anyone ruin your life

i have learnt a lot for the last 2 months. It was very unbelieveable situation where at the certain point you cannot trust your friend. the way they talk and behave are different with what comes into their mind. you will not know till you find that they treat you unfair. they are smart and use it to get benefit from others without considering other's feelings. how can your friend can do such of thing to you? my analysis is you cannot change somebody's character. if they are only think about themself then let them to do it and run away from them. treat them professionally, not personally!