That's an awful way to start off a fresh, new year. The executive board should really discuss this and come up with a solution. Mine would be a public and private apology. As a PTO president, my bosses are my board members, the parents, the teachers, the school staff, etc... My main job is to enrich the school and bad mouthing the teachers in an open meeting certainly doesn't do that. I hope your group can remedy this situation and proceed with a more positive year! Good luck!
Whether it's stated in your bylaws or not, you can bring the topic to a meeting and have it voted on. In this case, you could present it as either asking the President to formally apologize to all staff or you can seek to have the President dismissed from her position. If enough people in the room feel the same way you do, than whatever needs to be done will be done. It might be a bit hurtful to her, so you should think it through before proceeding. A bit more than she bothered to do.
You as a parent are the President's boss. The President is suppose to act in the PTO's best interest, if she doesn't, you need to call her on it.
At our first meeting this year, our PTO president made a comment that the only time we see the teachers at meetings is when they want money. Many teachers were offended and hurt, and we seem to be off to a negative start. What would you "seasoned" PTO people suggest the PTO board should do?