Can I trust my husband when he lies to me about his whereabouts.

We went out on saturday for a family meal. It was a lovely evening but on the way home my brother asked if anyone wanted to go to the pub for one drink just to finish the evening off. I had to return for the babysitter but suggested that he go thinking he would only be an hour tops. He left me at 10:30 and did'nt return until 1:35 in the morning and said my brother had abandoned him, whereas my brother states he went off with his own friends. He also lied about where he was and cannot remember getting home. How can I trust him when he finds it so easy to lie to me. I am allways honest with him.