Four short lines carry a simple, painful confession: the speaker ended a relationship and now wishes they hadn't. The opening line is blunt. "Letting you go was my mistake" doesn't dress the feeling up or blame anyone else. The speaker owns the decision, and the next line, "I understand it now," suggests this clarity came too late to change anything.
The last two lines shift from thought to experience. The speaker doesn't just remember the other person; they "still see your face / Everywhere I go." That could be literal in the sense of imagining a familiar face in crowds, or it could simply mean the person is impossible to forget. Either way, the loss follows them through ordinary life.
The mood is quiet, wistful, and a little raw. The plain wording and short lines make the regret feel honest rather than dramatic, as if the speaker is simply admitting something they've carried for a while.