Clean intro. Mixing on the vocals is pretty good, but it's a little bit too loud and seems to be in the wrong key. Did you take someone else's acapella and work around it? If not for that strange accidental thing going on, I'd give an extra star. Tip, if you have a vocoder software or something similar, you can make whoever you want sing whatever melody you want. I recommend iZotope Vocal Synth.
Also the transition in the middle kinda wigged me out. Very sudden. It eventually resolved nicely, but then there was that strange thing with the vocals. Interestingly, after that, the only notes that really bugged me after were on the words "(begg)ing you," "and true," and "you do." Take that up or down a semitone and it'd be basically fixed.