Legal Question in Personal Injury in California

Your posting appears to be a statement of your opinion. The only things that might be a statement of fact is that she overcharges, but that also is probably opinion as you cite no facts to support it. You would never have to get to the issue of whether it is false on its face [how can you tell if overcharging is false on not on its face?]. That fact that it is a poorly written critic is to your advances as it lessen the likelihood of someone think it is accurate.

The easiest thing to do is to remove the posting, although you might want to post that she threatened to sue you and perhaps include her letter to you. But I have not seen her letter so can not be sure. It is always a stronger attack to use facts if you can.

You can do as demanded to avoid the risk of being sued, or pay substantial court and lawyer fees to take a stand on your 'principles' and defend the lawsuit. Your choice. No attorney is going to guarantee you the outcome of litigation. You may or may not have a 'strong' defense of 'truth', but you won't know the actual answer to that until the case is over.

If you can prove you were overcharged, you have a good defense. Truth is an absolute defense in these matters... but it can cost you quite a bit of money. These SLAPP lawsuits, as they are called, require the plaintiff to meet a pretty big burden... but it could still mean substantial expense to you.

Good luck.