This is the literal translation. "Ne fregeris" (could be also "Noli frangere", same meaning) means "Do not tear/break" and "cor meum" means "my heart". It is hard to tell if Ancient Romans actually used this expression since it seems to have a recent origin (besides being a metaphor), anyway I think that a literal translation can work pretty well. About "Coy ne adito": it is difficult to interpretate what it means. "Coy" does not exist at all in Latin, the whole sentence might be a corrupt form of "Cor ne adito", which is often translated as "Do not rip your heart".