How do we unconditionally love and wish people the best?

Deep down, I know there is a core that wants to love everyone for who they are. No matter who they are to me, the world, no matter how terrible of a person they are, no matter how much they make me jealous. The only problem is, the stuff in the middle. I feel like I cannot move past things due to unclean closures to relationships and overall jealousy. I really want to wish everyone the best, but my intentions are tainted by negative emotions. How do we break through this terrible barrier that stops us from loving ourself and everyone else, and how do we unconditionally love everyone?