How to I stop being a vegetarian?

I became a vegetarian roughly two and half years ago (June 2007). Because I've been having some medical problems, many people have recommended that I eat some meat. To be quite honest, I really don't know how to stop being a vegetarian. I've accidentally gotten a hold of some oyster sauced once and it made me very, very sick on my stomach, almost like being food poisoned. I agreed to try to eat a little bit and then I burst out into tears. I don't know how to do this. What's a safe way to start eating meat again without getting sick. Btw, starting with fish first is out of the question, I would gag while eating any type of seafood even before I was a vegetarian.