You've already accepted an answer but I don't completely agree with the others.
As I've already commented, me matas is mainly the equivalent of the English idiom you're killing me
According to MyEnglishPages
The phrase you're killing me is an exaggerated way of saying that
something or someone is very funny.
This idiomatic expression means that the person you are talking to is
so funny that one could die from laughing.
It's also possible to use expressions like "it's killing me" or
"you're killing me" to mean that you are anxious about something or
when something is driving you crazy
Two different meanings are described above:
(1) A person is very funny
(2) A person is very annoying
Both of them are present in the Spanish equivalent. Notice that there is no sexual reference in the description of the idiom.
I think that my fellow Spanish speakers are talking about this other Spanish idiom that is registered in the D.R.A.E, our most relevant language authority
estar muerto, ta por alguien o algo [Be dying for someone or something]
- loc. verb. coloq. Amarlo o desearlo con vehemencia.
English translation: To love or desire someone with vehemence
I think that the expression in English "be dying for someone" exists and it got the same meaning described above.
According to the Longman Dictionary
be dying for something/to do something
spoken to want something very much
Summarizing: Both in Spanish and English, "me matas/you're killing me" and "me muero por ti/I'm dying for you" are different expressions with slightly different meanings. If you employ "you're killing me" to express that you desire someone maybe you can employ "me matas" in Spanish as well but that's not slang nor the main meaning.