Frequent begginer's mistake guys, especially with all of the misinformation floating around out there and nurtured by stores trying to sell more bettas by enticing buyers with the prospect of breeding.
Let's not scare away all the new members, eh? It is perfectly easy to give sound advice without barking orders.
Anyways, as Chrissi mentioned allready, male and female bettas can not be housed together. Male bettas will often fight females to the death, though occasionally females get the upper hand due to their short fins giving them greater mobility. Even if they get along temporarily, they will inevitably fight - and very likely kill - one another. So please seperate them as quickly as possible, even if it means keeping them each in a clean tupperware overnight.
From there, you have a couple of options. You could do a divided tank where your two bettas can see one another, but not fight. I warn you, these tanks do have accidents sometimes, and increase the chance of both fish dying if one gets ill. You could buy each their own tank - 1g is the minimum for the species, but 2.5-5g is preferable - and enjoy them as the solitary species that they are (bettas do not need or like company). Or, you could (depending on the other inhabitants of the community tank) keep the female in your community tank and get the male his own digs. Your choice.
As for your other fish being stressed... bettas are pretty scary fish! They are known to routinely fight and kill other fish, and tend to harass just about anything you put in a tank with them. Another good reason to remove the bettas; they are posing a threat to the wellbeing of your other fish. Might I ask what species they are, so we can determine if at least the female could stay in community?
