Dante has always known and seen Sonny for who he is. He will come around and support Sonny. Kristina has always had rose-tinted glasses when it comes to Sonny. She got a rude awakening and she needs to deal with it.
Yes, Sonny's behavior now can be explained by the medication, but he has always had a volatile and violent temper. As long as he is in the mob, these incidents happen.
I don't know where this is going either. I hate Carly, but I loved the S&C scenes. Carly knows Sonny best and she said all the right things to somewhat calm him down.