I would say that the reason the first one is incorrect is because saying "I've been being here" vs. "I've been here" doesn't add any more information about you being there and therefore sounds unnatural even though it might technically be grammatically correct. When you say "I have been here" it can be taken to mean that you've either been there until the moment that you've spoken or that you've been there in the past at some other time, i.e. "You've been there before". So, context is what differentiates those.
You can say "I've been doing something or other" as long as what you're "doing" isn't "being".
In your first example, "it's been being" isn't one verb phrase. The "being" is part of a gerund phrase which is why it sounds fine because it's acting as a noun.
In your second example, it sounds fine, and I think a native speaker would use it, but if we're being nitpicky, it does sound a little off even though it's totally correct. It's different than the "I've been being here" because in this example, the sentence is in the passive voice, so we need the extra being to do that. I do think it would sound better if it wasn't in the passive voice but rather in the active voice instead, like, "He'd been abusing me..." rather than "I'd been being abused by him".