Perhaps yes, Lisa may not have hit bottom, but consider that Paul is not a main character and PaleGrass had already placed a term in him which I seem to recall was Lisa's graduation. I think P.G. has given far too much importance to this character who is still a teenager and having him commit what he did is obviously a personal opinion, but he seems to have crossed the line always for blackmail that would be easy enough to overcome, see the Paul End1 result.
It has been argued and argued that Paul's blackmail would be easy to overcome, but most blackmail is easy to overcome, and yet many people don't overcome it. It's all about the choices Lisa makes. If you have her choose to end it, then it ends. But if she makes the wrong choice, then it doesn't end.
And yes, PaleGrass has suggested that there is a definite limit to how long Paul will be able to continue blackmailing Lisa. That doesn't mean that we've seen the end of it.
As for PG having given far too much importance to Paul's character, I disagree. I think that the storyline involving Paul has been handled quite well, apart from the problem of PG not making Lisa's motivations clear enough from the beginning. But I think that he's correcting that.