This probably is a preflop raise (I'm still finding my own way with preflop play).

I would raise the flop with this rationale - if MP2 (lag post flop) wasn't there, you would certainly raise UTG+2's opening bet - just because it's two to you here, at this stage I'm not prepared to put either on a monster. As it happened, facing the blinds with two cold was enough to knock them out - I would be more confident of knocking out their (dangerous) overcards if facing them with 3 cold.

From then on, if it comes back to you capped, it's certainly time to slow down and give a bit of respect. Turn and river, I would call a single bet to me or bet if it is checked to me.