My interpretation is that this song is trying to say that two wrongs don’t make a right. For example: “He couldn’t bring her back with a bullet to the heart in the back of the man that tore his world apart”. This shows, that killing the man, who killed the one he loved, did nothing. She didn’t come back to life. He threw his life away to get revenge, but he still feels the pain from losing his love. Whichever path that he would choose, he would still have to live with the painful memories, and nothing changes that. If he didn’t kill that person, he could have led a better life, and still feel the same way.
The song in my opinion is also trying to stress that you shouldn’t make hard decisions, when you’re in a state of anger and sorrow. You’ll only face the hard consequences, which could lead to you feeling even worse.
“Kiss it all better I’m not ready to go” could possibly meant as a representation of the anger and sorrow you’re feeling when you make the hard decision. They are the source of your anger and sorrow, that keep haunting you, the more you don’t accept the truth.
“It’s not your fault love you didn’t know you didn’t know” may represent your subconscious concern for the action your choosing to do. You’re asking yourself if you should do it.
Judging by the woman in the songs words, it’s sounds like she doesn’t want her death to be avenged. She just wants the man to be happy, so she’s telling him the key to that happiness.
Sorry about how long this is. It’s just a theory of mine, that I wanted to share.