Breaking it to the parents.?

My fiance and I found out I was pregnant the other day. Our big problem is telling his parents. My parents are going to be told in the next few days so we feel his should be too. This is where the problems start. His parents are very religious Catholics, and believe premarital and using contraception are wrong. My fiance is Spanish, and he doesn't agree with all the Catholic beliefs, like not having before marriage - otherwise we wouldn't be in this situation! Although I am fluent in Spanish I still think telling them will be cringe worthy. We have debated for days how to tell them, and still have come to no agreement. His older brother was in the same situation, although he was not engaged. It caused a major rift in the family, as in his parents still haven't fully forgiven him. Anyone have any ideas on how to break it to them in the best way so not to upset them greatly again?