I'm 16 and pregnant by my ex boyfriend, 18, how do I tell him?

You're under 18? Screw your boyfriend - that's not who you should be telling. It's your parents. Your boyfriend may come back to help, but I'm sure he won't be of TOO much help. He's only 18. Your parents iwll be the ones helping you raise this child if you decide to keep it. Talk to your parents and decide where to go from there.

By the way, have you seen a doctor to confirm that you're pregnant?

What you should do right now is to calm down and relax. You have to tell your parents about this so they can give you their advice. Also, your boyfriend needs to know about this. He should be responsible for what he did and should find ways to support the baby. Ask him about his plans so you'll know about the next thing that you should do. You might be scared right now, but then again, you've got to think that your baby is a blessing. Please cheer up. Life goes on and be positive.