Your son comes first - over a boyfriend. Your son breaking something of your boyfriend's is not cool, and there should be a consequence. However, you should not be more angry at your son because you might *lose* the boyfriend.
Its good that the boyfriend is taking an interest, but I am overprotective and I would be cautious about him wanting to take such an interest. How long have you been together?
Just think twice about your motives for your son. Me: 41
Two boys: 16 and 13
Laughter will cure life's ills. Have you had your laugh today?