Not saying you should do this, but here's what I'd do:
1) I'd send her an email or text message with the status of everything. Yes, she may not receive it, but I'd send it anyway.
2) I'd remove the dead snail. I'd put it into a baggie with today's date on it, and store it in the refrigerator. (Hm, I might double bag it!)
3) I'd clean out the tank, and do a 100% water change.
4) I'd get a new container for either the fish or for the ADFs. But since you think she may be hoping that the betta dies, I'd get a container for him. (Trying to impart the message that if she doesn't want him, I'd be willing to take him.)
5) Since he has fin rot, if you have it on hand, I'd treat his water with aquarium salt. I'd put the his container into the warmest area of the room/apartment. I'd also turn up the heat in the apartment, if possible.
No, I don't think you're being too emotional. I think you're being a responsible pet owner. On the other hand, I think your roommate should be limited to this kind of pet only: