Folding when an overcard comes

[asg]

This is a huge leak in my game.

Lets say I'm in position and raise 3x the BB while holding JT. Flop comes 44T. I cbet 3/4 the pot and am called. On the turn comes a K. He checks, I bet 2/3 the pot. He check raises all in. I call and he shows K2. Now I'm left with ~900 in chips and tilted =(