Okay so there's this guy i like... unfortunately he's taken.... should i go for him?

Okay, so i'm pretty but right now i don't have the nicest body (stomach especially). By the middle of summer i should be back in shape. Anyways, back to the point. So there's this i guy I like.... my friend used to like him so i tried to get to know him a little for her, cuz she didn't have any classes with him. But then i started falling for him.... i really liked him, but then we found out that he had a gf. My friend immediatley stopped liking him, but i tried and couldnt. We talk every single day. He's sweet and cute, but sometimes he can be a jerk. He does thinks you dont expect. For instance, whenever he sees me he says hi and we talk. he even leaves his gf to talk to me. but then, the minute he goes back to her, she is all over him litterally, and shes not pretty at all. I feel like they will never break up... this year they may not have any classes but next year they have 2 while i only have one with him. also, it seems like he really likes my friend (that i mentioned earlier) who used to like him too. it pisses me off because the only time he ever texted or called me was for her number, or wondering who she used to like/ date and he always likes her posts on fb and even comments on them like 2 hours after she posts them. Then he leads me on, and stops. He walks with me to the bus and then i expect us to sit together but he plops down and says im sitting with (another girl) so and so. In general, hes so cute and sweet. but at times he can be a jerk... a hot mess. Should i go for him or completely get over him?