Anxiety with boys

I have pretty bad anxiety and these boy keep flirting with me, sitting next to me, asking me on "dates" and stuff, but I really don't like them in a romantic way. Only in a friend way. The most anxious I get is when they sit next to me. I get really bad anxiety, don't know what to say, etc. This whole situation has just really stressed me out. I'm too scared to be like, "I don't have feelings for you." Any other ideas on how to help me cope.

How old are you? Thats important for the answer here.

I am 18.

Just because they are your friends, does not mean that you have to date each one, simply because you are single. Be firm.  Telll them the truth and mean it or they will keep pestering you and your anxiety will continue to rise. Growing up is hard. You gotta be tough and strong.  Unfortuantly we live in a climate where some men think it is OK to be pushy.  

There is a wonderful book called Why Does He Do That.  I wish I had it when I was dating, it would have saved me a lot of headackes.