I would've pushed preflop most likely, after the flop I would probably fold even though this seems weak tight to me. I really don't see the SB leading into two people, one that can bust them, with anything that you can beat. There are a few hands that he could lead with that your currently head of, such as flush with overs, straight draw with and over, etc. But even with those your only 50-50. So overall i would fold, yet i wouldnt be suprised if that is incorrect. This whole hand seems weird to me starting with CO limp preflop.