First date

Okay this guy has been asking me out on a date for a year. I always say no because I’m very insecure. For a few months during the school year he was dating someone, then when they broke up he has continued asking me out. But his ex is SO pretty likeeeee i cannot. I’m sosooo insecure to go, it’s like i want to go but this girl is drop dead gorgeous. I don’t want to miss a chance with a guy who seems to really be interested in me but my low self esteem is getting the best of me 😔😪 what should i do ?