You could do half Pro-mix and half perlite. I'd take my plant out of the dry soil and lay it out on newspaper. I'd cut off any rotted brown looking roots. Then pot in pro mix and perlite and water it in slowly til water comes out of drainage holes. I usually set my pots on top of trays filled with pebbles until they fully drain. In this case I would let the plant drain and then tent it,and put it in a spot that gets light but no direct sun for about a week. If you tent it (to keep humidity) make sure to take the plastic off for a little while each day so the plant won't rot. You can also leave it uncovered for longer periods each day so it will get used to the drier air in your home. After a week lose the plastic and acclimate it to a bright sunny spot.

Also a smaller pot may be a good idea since you've lost some leaves.

Part of the problem is the promix barely drains it just holds in a ton of water. Should it be a 50/50 mix with perlite? But isn't perlite bad for these because of the fluoride?

If the perlite is rinsed well enough with water before hand it shouldn't become an issue.