Anxiety about Sex

I almost had sex with my boyfriend of 1.5 years last night. We didnt though because he could tell i had bad anxiety... We taljed about it last night but I still have it and its noon the next day and I think it has caused stomach ulcers. I have so much anxiety about my first time and I really dont know how to get over it. I have the desire to have sex with him, but the anxiety gets in the way. Has anyone else felt this way and how did you get over or cope with it?