Do your bylaws should have a clause for board member removal. I just created one for our bylaws thanks to these boards, and that may be a way to go. Is there a higher authority to appeal to (like will the Principal sit in and discuss). You need some mediation...maybe a past president that will act as a sounding board. You cannot continue with such discourse or the volunteer well will dry up.
How long is the current President's term? If there are elections coming soon, find someone to run against this person.
If you are "stuck" with your current President, then I suggest that the rest of your board try again to sit down with her and rationally discuss what the purpose and goals are of your parent group and how to achieve those goals. No accusations, no personal attacks, just a discussion of why the group exist and how to make it successful. Hopefully it can turn the focus back on the school and the students-the real reason the parent group should exist, and maybe it will help some of those who are in it "for the glory" to see how misguided they are. Would your principal be willing to step in and lead this discussion? It could be helpful to have someone sort of out of the conflict act as your facilitator.
I am in desperate need of some adivce, our PTO is falling a part to say the least. We had our president resign in the middle of the year and that made the VP president. We have struggled all year to become unified and most members are in this for the kids but others are in it for the glory of being patted on the back. The majority of the members want to fold and start over, and they are hoping that the president with just resign as that is where most of the problems are starting. Nothing in our bi-laws state anything about terminating someone. We have attempted to speak with the president about the issues but she just gets mad, and talks about it with other outside the PTO and we look like a bunch of high school kids. HELP.