The vet insurance won't probably help you on this illness because it's a "pre-exiting condition". Most insurances (one we have) has a 30 day waiting period before benefits start.

Maybe the vet will do payment plan for you.

I would definetly get the heart murmur checked out. I have experience (brief) was not positive out come. Heart murmur was found along with Feline Leukemia, I know FL was major cause of death not certain how heart murmur fit in to things.