I have a breeding pair who occasionally have a domestic in the tank..
What sort of bullying is it? As some males do try to dominate, but then again females can be just as bad - with angels it's a case of personality.
I believe the only way to sex them is when they are actually laying & fertilizing the eggs, however my females have always seemed to swell for about a week before laying the eggs.
How large is your tank? They prefer a lot of room when in groups, and a spare tank for the pair & then the fry is also required. Bare in mind that most captive bred angels have unfortunately lost some of the ability to care for the young once hatched.
Regards,