Too Jealous?

So im just wondering if there's a way to stop getting jealous. I hate the feeling it gives me. Especially tonight because we do concessions for our schools football games and this other girl was helping too. Now she is always talking to him and standing too close for my comfort. But tonight he was in the back helping make the hotdogs and i was taking orders. We had to call her in to help us and she went to help him almost the entire time she wouldn't leave his side. Then there was basically no one coming up and they were talking and he was laughing. Like really laughing while i was not more than 10 feet away siting alone. I almost started crying and i would have if someone hadn't walked up. Am i being too jealous? And i feel bad because they are on the same XC team and so they have to get along. I just dont want to feel this way anymore and i dont want to get in the way of him and his friends. we've been dating for a little over a year now.