Sorry about your loss, Terry0982!
But please do keep your mollies in salty water. 5g per litre will do the job nicely, and you can still add all the guppies, platies, and swordtails you want. They don't mind the salt. Nor do a variety of other fish, from glassfish and gobies through to halfbeaks and some cichlids. It's basically (most) catfish and virtually all tetras and barbs that don't like it. Most hard-water tolerant plants are find with a little salt. There's a nice list in the brackish water section of this Forum.
I do wish aquarium stores would tell people mollies need salt. I know some people manage without the salt, but as you've seen, this isn't always the case. Adding salt does no harm to the mollies, so it's an excellent "belt and braces" approach if you want happy, healthy mollies.
Cheers,
Neale