Hi Jesus and
to the forums
You don't have any breeding experience, correct?
This is why it's very important to research everything about budgies before allowing them to breed. Even if mating occurred, there are many ways to discourage breeding as well as egg-laying.
You need to put the mother in a separate cage by herself and let the father take over the rearing of the chicks. The mother is aggressive because she's trying to start a new clutch of eggs, which you need to discourage immediately.
Put her in her own cage, arranged differently and in a different room to throw her out of the breeding mood. The father will continue caring for the chicks at this time.
How many chicks are there? What diet are they on?
Please be sure to read through ALL
the Breeding Budgies stickies and articles
, in addition to browsing the rest of the forums.
Please keep us updated on how things go!