How to explain to your boyfriend that you are pregnant? we are teens.. HELP!?

You shouldn't have to explain anything to him. If you are old enough to be having , both of you should understand that all forms of birth control except abstinence fail. That should have been in the back of both your minds constantly. Wait until you are sure, then just tell him you're pregnant. You should have already decided what to do in this situation, that comes with being an adult. Do not make a sentimental decision about what to do; do what is right for the child first, then what will work out best for both you and your boyfriend.