I honestly think you got pushed off the better hand. It is so tough to make those marginal decisions in that spot though, heat of the moment, I've been there before.
This is why I don't like raising UTG with such marginal hands, what's wrong with a flat call? If anyone is observant which I assume most are, they might be very leery to the fact that you ARE limping in first position, which could mean KK or AA. Then if the pot gets raised, you might want to go ahead and reraise preflop to have people think you're on the kings or aces.
Also, with regards to continuation bet sizes, what's wrong with just betting the same amount preflop or just a tad above your preflop bet, like 350? You find out the same information at a cheaper price, my two pennies.