Domestic abuse is never the fault or responsibility of anyone except the abuser.
It is extremely common for an abusive person to say that “it’s your fault”. This is just another form of abuse.
Your partner is an adult and makes a choice about the actions they take.
They could choose to walk away from the situation, but instead they choose to be abusive.
Regardless of the form the abuse takes, it is completely unacceptable and is never your fault.