That depends on what the promise is, and whether or not you feel you can trust him.
You Should Keep contact with your ex-boyfriends so you guys dnt hate each other it's the rite thing to do
No.
of course you should its a great opportunity to make friends
if your super close to his friends... believe them. but if their more like his friends then some what believe them if its about a girl talk to her. . honestly you wont know the truth till you hear it from the other person.
No because you will be messed up to and be crazy!
ask him.
One of my ex boyfriends!
they be jealous
no
Well that depends on how old you are and what kind of relationship you and your ex shared. If you and your ex are still mates then you should talk to him about it. If not then just go out with his brother it's got nothing to do with him.
That would be a real back stab to say okay, I don't think you should.
yes give him some of his own medicine!!