I haven’t been over watering it if anything I wasn’t eating enough but I saw this little leaning to the side and leafs starting to come off. The other two plates next to it are prefectly fine.
The stem is rotting. If the leaves are firm, you might be able to use them to propagate more. Lighten up the soil more with more perlite, turface, cinder or sand, and plant in a small terracotta pot so it can breathe.