Depending on how strictly catholic or traditional your parents are..it might be hard telling your parents but they'll understand, and can help you through it.
Had a friend that experienced the same thing, she chose to abort without telling anyone except her boyfriend and close friends. It was a hard choice but at that point in her life, she wasn't ready for a child, couldn't financially support a child and came from a strict family (very traditional) who would have disowned her, so it was the best option for her.
You really need to think about how its going to affect your life and whether or not you can put your life on hold for awhile to raise it (although your parents and friends can help you there) or prepared to put it up for adoption later if you choose not to abort.
You're not alone, there are heaps of people you can talk to:
http://dailystrength.org/support/Childrens_Health_Parenting/Pregnancy_Teens/
or call the kids helpline and get them to put you into contact with people that can help.