Ethically, a T should not continue to see a person when she feels that she cannot work with them or be useful for them anymore. It would be unethical to continue to see the person in these circumstances.

You can be unhappy that your T was not able to tolerate all the stuff you put upon her but ethics do not and cannot say anything about how much a particular therapist can or cannot tolerate. This is personal judgement.

So, I think there's no real basis for suing your ex-therapist. Of course you can still do it anyway. But it just feeds the stigma related to borderline'ish people - that it's risky to work with them because if things don't work out then they might sue you on an arbitrary basis.