Its often very tempting to try to be nice, keep the peace, try our utmost to make sure its not our fault.
But sometimes it is really not you. Sometimes its really the other person and they are really toxic.
Keeping the peace and playing nice will never help unless somehow they can find change within themselves. No amount of pleasantness is going to change that.

In a situation like that there comes a time when you have to cut your losses and disengage from such toxicity because its negatively impacting your life.

So maybe you should limit contact to the absolute minimum possible. Avoid places where she is as much as you can. Its sad, and it may feel like defeat but it can actually be a liberation.