You can't cross a bridge you've burned

I'm so tired of being stabbed in the back. I'm tired of helping people get what they want, only to find that once they've obtained it, they forget who helped them get there. I'm tired of doing things for others, only to find that when I need help with something, they're no where to be found. Most importantly, I'm tired of forgiving people for hurting me over and over again. I'm done. You can't cross a bridge that you've burned, and I'm done reconstructing bridges. These people are going to look up one day and realize that they're all alone, with no one to blame but themselves... but they needn't bother calling out to me because I'll be long gone by then.