The poet is addressing the reader, which is you. He is saying that even though he is not talking directly to them, he still feels like he can address everyone else but them. This is because no one else is responsible for his feelings. In addition, the reader is also being referred to as "you" when the poet says, "And now that you know how I feel about you, / You have the right to know how I feel about other people." Here, the reader is given the opportunity to understand the poet's state of mind by knowing how he feels about a particular person. This implies that the reader is that particular person who is being talked about. Furthermore, the reader is also called "you" when the poet says, "You should blame yourself for my pain / Because if you didn't exist, then nothing would prevent me from feeling this way." In this case, the reader is being told that they should feel guilty because they are responsible for the poet's feelings. If they didn't exist, then the poet would be able to deal with their absence easily enough without feeling bad things about them.