friend now hangs with the a pot head

[Chrisal23]

So long story short my ex wanted to date this guy who apparently has game? I honestly don't know what she saw in him because he didn't care about school and he smoked ect. I almost hated this guy for trying to get with her but at the same time kept my cool and also felt pissed that she wanted to be with him too. This guy has been in the picture from the very beginning and I was dumb enough to let it slide with my ex because it really bothered me, and should of just not persisted on being with her. She obviously felt something for him since they still talk and chill. Anyways my best friend knew this and his little brother started to hang out with him. At first he would be on my side saying he didn't like him especially since he was being a bad influence with his brother. My ex told me that he chills with this guy that she had/has a crush with. What makes me mad is how in one side she tells me this but she also chills with him! I feel like noone is on my side. I feel betrayed from both her and my best friend. It's a mixed feeling. He did this shady and never told me about it, and that's what really ticks me off. Ofcourse I won't try to control who he chills with but damn it felt bad with this whole situation. I dont know if I have a right to feel mad or not but I do. I honestly don't clearly know what's going on. I would appreciate any opinion.