lorax

First step is to separate off some of the pups (which you are calling trunks) - the clumping is probably holding water, which as you have noticed is bad for the plants. There are many threads here on the process of pup-separation - just use the built-in search feature.

Are all of the stems mooshy, or just the central one? Has your banana ever fruited? Do you know what kind of banana it is? If any of the stems are firm, separating them will save that plant. Equally if you have mooshy stems, you can cut just below where the moosh stops (if it stops) and save those plants as well.

Welcome aboard! Wish it was under other circumstances, but all is not lost!