I hear ya.

First accept that mothers are hard to break but if she let you have a BP then she is probably pretty cool about it.

Second, be sure you have the time, money, and plan well ahead.
How old are you? I see alot of cats living at home buy snakes and then when they go off to college the snake ends up being taken care of by the parents. Most times the snake does not receive the same level of care and attention.

Third, buy books and make your mom watch snake shows. Before I got my RTB I bought a book and left it in plain sight for my wife to see. Showed her countless videos and I assured my wife that it would not eat the dogs.