They just go into solution. There are other metabolic reactions that will eventually use them up. To prevent acidification, the cell also has mechanisms to pump protons out of the cytosol if too many protons start building up.
Am I right in saying that when the ethanol is oxidized to acetaldehyde, the acetaldehyde is oxidized to acetic acid, which is used up in the Krebs cycle?
What is the balanced equation for the oxidation of acetaldehyde to acetic acid?