I don't think forgiveness has to equate to taking him back. Eric said to Nicole a few weeks ago, "I forgive you, but I can't trust you." and I think that actually could be applicable to Sami's situation. In my mind, forgiveness would mean stop the revenge plan, nothing else. I agreed with Caroline when she said, "Set yourself free."--there's no reason for Sami to allow EJ's behavior to dictate her own for the rest of her life.
That being said, I think Sami's reaction to Caroline is going to be much like Nick's seemed to be to Julie, when he would try for about 30 seconds to stop his plan and then go back to what he was doing.