Meaning of "just about everybody else has" in this context

The utterances

• - I ever tell you how much she depends on you?
• - I ever tell you what an asshole you are?

Are missing the initial (and totally predictable) Did at the beginning; that's what the hyphen represents. This is called Conversational Deletion, and it works from the beginning of a sentence, optionally deleting any completely predictable word, then optionally deleting the next one, and so on, until it runs into a word that's not predictable. Then it has to stop.

The I in these utterances could also be deleted in conversation, since it's clear what's being asked.

• - Ever tell you how much she depends on you?
• - Ever tell you what an asshole you are?

Some other examples, with example numbers from Chap. 1 of the dissertation in the link:

• (16) Gotta go now.
• (17) See you next Tuesday.
• (18) Too bad about old Charlie.
• (19) No need to get upset about it.
• (20) Been in Ann Arbor long?
• (21) Ever get a chance to use your Dogrib?
• (22) Ever get to Japan, look me up.
• (23) Good thing we didn't run into anybody we know.
• (24) Last person I expected to meet was John.
• (25) Wife wants to go to the mountains this year.

The utterance Everybody else has, on the other hand, is not merely colloquial like Conversational Deletion; it's an example of VP Deletion under identity. The Verb Phrase that gets deleted is something like

told you how much she depends on you and what an asshole you are.

which is made up of the verb phrases from the previous sentences. These are past tense; but Everybody else has uses has instead of did, so it must be a Perfect construction. That means past participle told (used after have), instead of infinitive tell (used after did).

The options are:

• "...everybody else has." (the rest is elided because of parallelism, the redundant can go unsaid.

• "...everybody else has told you." (nothing is elided, and it makes a complete sentence)

Just "...everybody else has told" doesn't work; 'tell' requires an object.

Yes; The implied full form of the sentences would be:

[Did] I ever tell you how much she depends on you?
[Did] I ever tell you what an asshole you are?
Nah. But that's okay, just about everybody else has [been repeatedly telling me what an Asshole I am].
 They both laughed.