Alright, I suggest heading out and getting two medium-large 'Kritter Keepers' from the reptile section(they hold up a little better then the ones from the rodent section). They're not that expensive, have a nice secure lid, easy to do water changes in, and are safe to heat. You'll also need two small submersible heaters, thermometers, and probably some silk plants for each.
Regularly these tanks should be changed 2-3 times per week 100%, though since your girlies are injured probably wanna bump that up to 3-4 times to keep the water extra clean, and just add a couple teaspoons of dissolved AQ salt to the new water with each change.
Here are the forum betta care stickies ;)