Hi rsz
I'm so sorry to learn that your gourami died.
But before you replace him with either another gourami or a betta, there is something you might want to think about. That is: are you absolutely certain that it was male and the one that you have is female?
There are a couple of reasons why I am asking this. First, I have never seen a female blue dwarf gourami. Where I live they just do not sell them. (If I ever do, I'll buy it faster than you could blink your eye!!!! ) According to the man at my lfs, they would get them in stock if they could, but they cannot find them. They do not seem to be on the market here. The same goes for all the other fancy variations on the dwarf gourami. The excuse they are given is that the female is so plain and ugly that nobody would want one. (Yeah, sure!
)
The second reason is because it is unusual for a female gourami to be aggressive toward a male gourami. It's very unusual!
Do you have a picture of them?
It really sounds to me like you have an aggressive male rather than a female and if that is the case, your best bet might just be to leave him alone. He will just fight with another gourami and since a betta will occupy the top of the tank, which he has claimed as his own, he will fight with it, too. Even if it is a female, if it is aggressive, it's best to keep it alone.