Life as i know it

So i have a boyfriend and we are doing long distance i miss him terribly but thats normal. But told i was at kansas state fair and there was couples holding hands well i have a new friend named matt and i have a crush on him but he is younger and again i have boyfriend i am needing advice to keep him just a friend even though my teen hormones say more. I will not break up with my bf unless he is ready to and even then it would hurt. I just need advice i want to hang out with him like as friend and invite him to bday because i have no friends that can go i need two friends to make my birthday party fun and he is the only one that has said yes because one of my friends who might be able to go. Is it appropriate to have a crush at your bday party.