Help! Boxer and Bulldog trying to kill each other!?

I have had a female Boxer (Izzy) for over a year. Two days ago we got a male English Bulldog (Lewie). I knew it might take them a little while to get used to each other and be friends, but they HATE each other. They can't be in the same room without a rowdy throw-down - I'm talking fur and blood flying! I don't want either of them to get hurt, so I keep separating them. My husband says we need to let them duke it out until they determine the Alpha dog and then they'll chill out. Is he right or am I going to end up at the vet with a dying dog?