RJ Mitte -- I Feel Terrible ... I Didn't Mean to Laugh at Murder

RJ Mitte looks like he's aching with sorrow over his comments about the woman who claims to have killed between 22 and 100 people ... saying his words came out wrong and he's really sorry.

RJ was coming out of Pinz Bowling Center Monday night when we asked him about Miranda Barbour and he went off on how hilarious it was.

RJ now says he was really talking about "Dexter" and it just all came out wrong.

Fact is .. we did say Barbour was kinda like Dexter so point taken.