Slept with niece

I slept with my niece (21) me (37) on a family holiday, I paid for her to come to help me my wife and my 3 children all under 8 as my wife was just recovering from post natel depression and we was going through some difficult time.
She instigated the whole situation while me and my niece went back to the hotel room to collect everyones swim wear and inflatables while my wife and children wear waiting at pool side
Was totally wrong in every way but couldn’t resist