Do I have to be more involved with my boyfriend's friends? I really don't want to.
Why would you not want to be involved with them?
His ex gf also had issues with them, so I'm not the only one.
Well, it sounds like the two of you might be on to something there.  It's fine, nothing says you have to like or talk to everyone your SO is involved with!
Good, from what I already know, I don't want to know any more about them.
They sure don't sound very fun. It's good that you have decided to surround yourself with people that you enjoy.