Tired!!!

I'm on my 14th week pregnant! I drive an hour to get to work and my boss has been working me such long hours.. I worked last night from 5pm to 7am! Totally drained today! Nauseous and aching! I feel like I'm being a cry baby because I'm so tired and exhausted! I try to explain to my boss that I'm tired and can't work like this but they aren't getting it! What can I do? They aren't letting up! Ugh help! Any suggestions?