Start documenting everything. Forward your emails to your personal email. Get all your employers request in writing or email. Have a direct and frank conversation to see what thier reservations are. Even though you love your work it sounds like they don't love you.

As unfair as it maybe you may want to cut your losses. A legal fight will be ugly, stressfull and not a quick action. If they are confronted it may indicate to them your are still on your toes just otherwise abled. Or they may get defensive and just excuse away thier behaviour.

I am so sorry you are experiencing this. I know what it feels like as I am kn a very similar boat.