The text of Mozart's canon V'amo di core is
V’amo di core teneramente, si, si!
Io non vi posso altro amare no, no!
Uh, che dolore, uh che tormento, uh, uh!
Clearly the "V" and the "vi" means "you" here, but what is the exact grammatical role? Is it a single person or several persons? And does the second line indeed mean "I cannot love someone different from you?"?