In short, I have a song melody. I want to record a voice. I record a measure, hit right notes (from the melody), then I record the next measure. I can’t sing the whole chorus at once (8 measures). Because I know that I will ruin the pitch. Your suggestions?
I'd recommend you sing it 8 times, top to bottom, rather than pull up after every line.
The flow will be significantly better.
If you use a multitrack-capable DAW, you can then do what's known as 'comping' - you listen to each version then edit together the best of each line, in such a way that you can't tell they were from different takes.
The probability is usually that you can immediately discount the first 3, unless you properly warmed up first.
Depending on if you think you will ever need to go back & re-edit, you can then discard the other unused segments & bounce the result to a single track.