I think the hardest thing to do is trust God. To completely give something up and admit that you don't have control over it. I wish I could change peoples hearts or their outlook on life but I can't. I can only be the example and share encouragement. It is so hard to see people you love going down a hard and treacherous life path.
Iv'e learned now that you can't change a person and with that being said God would not want you to continually get hurt or beat down by a person. God does not say life will be easy or effortless but He has designed us to live a life full of joy. Be careful who you choose to be around because they can either build you up or completely strip you of your love for life. These people who affect you negatively may mean a lot to you therefore you can't just kick them to the curb, and you shouldn't.
Be aware because it can come to the point where distance is healthier for both of you, if you continually enable a person and say their actions are ok it will not benefit them. Remember, YOU CAN'T CHANGE SOMEONE.
Create healthy distance, forgive them and pray for them. Don't continue to get smacked around. Don't let someone rob you of your joy. Don't let someone treat you less than you deserve. You are a child of God; I don't believe He wants to see you stuck in harmful relationships.
You can't change them; they have to make a conscious decision to follow Christ in order to see transformation and you can't make them do that either.