I think what he's talking about is a relationship that turned toxic. He's talking about how this person has put him in such a low place and that even though he's tried to get this person to stay he's now starting to realize it's no longer good to try to make an effort in getting them to stay like where he says, " You used to be all that I needed" and "Oh God I wish you'd just speak to me." It sounds like they had problems in their relationship and instead of telling him, they left him. He also thought that he can still have them in their life as a friend but he realized that they were doing more harm than good and that's why he said, " I need to cut you out." Also, that this person and him used to be in such a great relationship but that's now just turned toxic. So, "The Black" being the sadness and emotional problems caused by the toxicity of the relationship that the person has caused him.
I think what he's talking about is a relationship that turned toxic. He's talking about how this person has put him in such a low place and that even though he's tried to get this person to stay he's now starting to realize it's no longer good to try to make an effort in getting them to stay like where he says, " You used to be all that I needed" and "Oh God I wish you'd just speak to me." It sounds like they had problems in their relationship and instead of telling him, they left him. He also thought that he can still have them in their life as a friend but he realized that they were doing more harm than good and that's why he said, " I need to cut you out." Also, that this person and him used to be in such a great relationship but that's now just turned toxic. So, "The Black" being the sadness and emotional problems caused by the toxicity of the relationship that the person has caused him.