Talking to a guy for 3 weeks.. just found he has a girlfriend!

So I met this guy about 4 weeks ago, and we hit it off. He only had my snapchat because I didn't think I would eventually end up liking him so I didn't ask him for anything else. We talked all day and went on dates every week (sometimes two dates in a week). It was amazing. I'm fairly new at the dating scene, so when he was gentlemen and nice to me, I quickly began to like him. We talked about everything and got along so well. The last week of seeing each other, we were already kissing, holding hands and doing other things.(not sex) One day, out of nowhere he deletes me off his snapchat without any explanation! So I find him on facebook and right when I find him, I see a picture of his gf and him kissing. It made me so mad and a little hurt that a guy can do that to his girlfriend of 2 years. We're in college, so I think he was just trying to get one thing from me. It SUCKS.  She lives in Hawaii. He's out here for college. I really don't want to get involved with their relationship, but how can someone do that and not pay any consequences? I would want someone tell me what my BF is doing when he's at college. His roommates are assholes because they would see him hugging  and kissing me. His roommates are from his hometown too! It took me by surprise because he didn't seem like the type. He made me feel important.. :/ guys are assholes...