If you want your message to be understood by those who understand txt language, feel free to use it.
However, if you want your message to be understood by everybody, it is best to use proper grammar (not grammer). That way there is less room for confusion and misinterpretation.
And while we’re on the subject, do we all know the difference between people and things? When referring to people we use the word “who.” “That” is reserved for things.
Wrong: The man that was walking down the street . . .
Right: The man who was walking down the street . . .