Here's a page out of CBT....

Two Lists: Evidence this is true Vs Evidence this isn't true

Rapid thoughts, not just about your brother but other men in general. Now consider the likelihood of veracity of each.

Another two lists: Evidence you are worthwhile vs evidence you feel you have trouble in this respect. Again rapid thoughts and asess the veracity of each.

Combine the two lists together.

Your brother sounds like an arrogant jerk that I wouldn't want to be remotely like. Besides, it seems he is incabable of holding down a relationship.