I dont know why it happened?

I went out in the morning to keep d dumpster outside from the backyard door and my husb got out from d garage door to leave ind morning..when he left he closed d garage door and i thot how will i get in..it never clicked me tht i came from backyard so tht door wud b open ...i borrowed a phone and thot of caling him..by the time i c him cming back..he asked me - where di u enter d house from? i was stunned coz i dint think abt it... whats rong wid me ...i feel so sick and frustrated wid myself.