I'm a fatalist. Once TB is in, in it's in forever. And you have probably accidentally transferred it into other tanks, via nets, water hoses, etc.
I have kept blue gularis, and even bred them, though not as well as many other hobbyists. They take serious research, and are the kind of fish I don't think you'd like. You crowd your tanks and build communities, and that fish is not for community tanks. I'm happy with that, because my norm is lightly stocked single species tanks. If gularis were a little longer lived (18 months to 2 years) and more available, there'd be serious unemployment in the world of pet store bettas.
They pay attention to their world and recognize their people.
Blue gularis will eat what fits in their wide mouths, but the main knock on them is their need for cooler water. Not too cool, as in Fahrenheit, 70-74 is good. Kept warmer, they age rapidly and live a year. They also don't like each other, and can be very aggressive together in small tanks.
Interestingly, I have never seen signs of TB in my killies. I don't know if they have defences or if it's the tank set ups, but visible TB seems rare, and when I have kept them in tanks with other fish and seen Ich, it's not on them. Sometimes when I get too many scrapping males, I have to put one in a QT tank, and when new fish come in, they seem extremely resistant. But Oodinium spp (velvet) slays them.