Kenneth Petty

Nicki Minaj has a long history with her new boyfriend, because she first fell for him when she was a teenager -- and she feels he's changed since his checkered past. Sources close to Nicki tell TMZ ... her first relationship with Kenneth Petty happened when she was a 16-year-old living in…

2:30 PM PST -- Nicki just admitted to the allegations, writing, "He was 15, she was 16 ... in a relationship. But go awf, internet. y'all can't run my life. Y'all can't even run y'all own life. Thank you boo." Nicki Minaj's new boo is a registered sex offender with a disturbing rap sheet that…