My crush has a rude and controlling girlfriend

So this guy I had a crush on I dident know he had a girl freind and so I was like ok. So I stopped crushing I guess. But I became freinds with her and the guy is my best guy freind and I think I have a crush on him again. She is rude and controlling and possibly cheating on him and he talks to me about his relation ship.

And I freinds with his cousins and so I see him a lot. He is realy flirty when I txt him.

Should I pursue liking him....