I, too admire you for keeping your cool. You are obviously more mature than b/f's mom is. The issue is really between b/f and mom, though, in spite of the insults leveled at you. He needs to stand up to her and defend you now. Otherwise this incident will just set a precident for many many more scenes in the future. He really needs to assert himself as an adult with a separate identity and life of his own. Good luck to the two of you!