Stop feeding them so much. Your female sounds like she has bloat. only feed them 2-3 pellets per day, for 6 days a week. the 7th day they need to fast. Dont feed your female until her belly goes down. Go to bettafish.com to get more indepth information from betta fish breeders and experts who can better asses what killed your male and help you care for your female better.
It might meen that your betta fish is about to lay eggs.
Np, but they will bite. Yes, they will fight to the death.
yes
She breeds with a male Betta Fish.
it looks like they have a big bubble in their side
No. Betta fish will attack each other no matter the sex.
Yes they will.
Your betta fish is a female if she has smaller fins than an average male.
The Betta fish want to kill eachother. That's what all Betta fish want to do, that's a natural thing.
No.
the female betta fish are released from a vent while a male embraces her
male