I'm sorry you're going through this. Some employers do this when a person uses FMLA. Document, document, document. Every time you send an email, print a hard copy. Log and print your IM's. Even if you don't want to deal with a lawsuit, you don't want something coming back to bite you that will hinder your job search should it come to that.
Hang in there. I'm sending lots of good thoughts your way.
