I do not think there is one person in my family that shares my interest in snakes, including my wife. Obviously since I live with my wife we had to reach some middle ground. I used to house my snakes in my wife's wash room but have recently built a building out back for my snakes. Now both of us are happy.
It does not sound like your mother has given you an ultimatum so it does come down to your ability to properly care for this snake. Do what is best for both you and the snake.
I salute you for being so close to your family. Remember they can never be replaced, but in this situation it does not sound like keeping or selling this burm is going to split your family.
1.0 Bearded Dragon, 0.0.1 Canebrake, 0.0.2 sulcatas, 0.2 Eastern Diamondback