Loving at no cost

Sometimes I wonder why God wants us to love everyone even the ones that don't deserve it. There are people I have met over the years that don't seem to deserve love but in the end other people tend to have that grace to love them when I can't seem to do it.. Guess God really wants me to learn that one. We were reading Romans 12 last night and a few things really stood out to me. For one thing, we must be sincere in our love. Not fake or showing off that we love, because then it's not from the heart. It would be better to not show any love if its not from the heart and sincere. The other thing that stood out to me was verse 17. Do not repay evil for evil. That is a hard one for me. People hurt me, I want to hurt them back. If people ignore me and treat me bad, nothing in me wants to love them at all. I tend to lean towards the "if they don't treat me right, then why should I treat them right". God is asking me to love. That includes all my friends who will have nothing to do with me, that includes all my family who thinks ill of me, that includes all the people who have hurt me over time.
I get so frustrated because I do not really understand the reasoning why that no matter how hard I try to do things right, my friends and family seem to think I will never be different. I want to be a new image, a new being that God looks on and says with pride in his eyes "that's my daughter and servant". But then again, that's way off the subject of love. Just that I need to love the people that despise me or talk bad about me and don't have hope. I still need to love them with an honest love.
I pray that the Lord will open my friends eyes to see that no matter what people do in their lives, there is always hope for them and even when they give up hope on me, God will always be there for me..

Romans 12:9-20 Love
9 Love must be sincere. Hate what is evil; cling to what is good. 10 Be devoted to one another in brotherly love. Honor one another above yourselves. 11 Never be lacking in zeal, but keep your spiritual fervor, serving the Lord. 12 Be joyful in hope, patient in affliction, faithful in prayer. 13 Share with God's people who are in need. Practice hospitality.

14 Bless those who persecute you; bless and do not curse. 15 Rejoice with those who rejoice; mourn with those who mourn. 16Live in harmony with one another. Do not be proud, but be willing to associate with people of low position.[c] Do not be conceited.

17 Do not repay anyone evil for evil. Be careful to do what is right in the eyes of everybody. 18 If it is possible, as far as it depends on you, live at peace with everyone. 19 Do not take revenge, my friends, but leave room for God's wrath, for it is written: "It is mine to avenge; I will repay,"[d]says the Lord. 20 On the contrary:
"If your enemy is hungry, feed him;
if he is thirsty, give him something to drink.
In doing this, you will heap burning coals on his head."[e] 21Do not be overcome by evil, but overcome evil with good.