On tenure track and department chair wants me to consider leaving
As an untenured faculty member your options are limited and the risks are high. Depending on local law you may have some protections, of course. 

What you do depends on what her actual power over you is. If she is part of the tenure decision process, then the situation is worse. Likewise if she can influence others. 

But, she may just be signaling you that your tenure decision is likely to be negative, whether from her actions or just a general assessment. You don't say, for example, how the research is going or the state of the grant (or even if it has been awarded or is just being applied for). 

You will probably learn more when this individual meeting happens. Sadly, you won't have any other person present who can support you or attest to any improper statements if they occur. I've been in such a situation, actually. 

My suggestion is that you immediately get into the job market and start to collect colleagues who will support you both in finding a new job and in maintaining this one. Long term, it doesn't seem like this environment is supportive enough. 

If she has doubts about your work, her response should be about how she can help you. That may be her intent and you aren't recognizing it as such, but it is impossible to say from what you write.